The Mean Value Theorem is the most important theorem in calculus. It is the first theorem which allows us to infer information about a function from information about its derivative. From the MVT we can derive tests for the monotonicity (increase or decrease) and concavity of a function.
1. The chain rule describes how to take the derivative of a function composed of other functions. It states that if z = f(x, y) and x and y are functions of t, then the derivative of z with respect to t is the sum of the partial derivatives multiplied by the derivatives of x and y with respect to t.
2. The chain rule is applied to find the derivative of two example functions, w = xy and w = xy + z, with respect to t along given paths for x, y, and z in terms of t.
3. The chain rule is generalized to the case of a function u of n variables, where each variable is a function of m other variables
The document introduces approximations of the area under a curve using Riemann sums with rectangles. It explains left and right Riemann sums, showing how to calculate them by dividing the area into equal subintervals and determining the height of each rectangle. While Riemann sums provide approximations, taking the widths of the subintervals to zero provides the exact area under a curve, as shown in a video clip about the concept. Riemann sums have applications in economics for determining consumer surplus and in science for modeling phenomena like blood flow.
The Rational Zero Theorem provides a method to determine all possible rational zeros of a polynomial function. It states that if p/q is a rational zero, then p is a factor of the constant term and q is a factor of the leading coefficient. Descartes' Rule of Signs can be used to determine the maximum number of positive and negative real zeros by counting the variations in sign of the polynomial function and its substitution of -x. It provides bounds on the number of positive and negative real zeros that are either the number of variations in sign or less by an even integer. The example demonstrates applying these methods to determine all 16 possible rational zeros and the bounds of 0 positive and either 3 or 1 negative real zeros for the given polynomial.
critical points/ stationary points , turning points,Increasing, decreasing functions, absolute maxima & Minima, Local Maxima & Minima , convex upward & convex downward - first & second derivative tests.
This document discusses finding the maximum and minimum values of functions, as well as points of inflection. It provides instructions on how to find the coordinates of turning points by setting the derivative of the function equal to zero and solving. It also discusses how to determine if a turning point is a maximum or minimum by taking the second derivative and checking if it is positive or negative. The document concludes by giving examples of how to apply these concepts to optimization word problems involving areas, volumes, or other quantities that need to be maximized or minimized under certain constraints.
The document provides information about Lagrangian interpolation, including:
1. It introduces Lagrangian interpolation as a method to find the value of a function at a discrete point using a polynomial that passes through known data points.
2. It gives the formula for the Lagrangian interpolating polynomial and provides an example of using it to find the velocity of a rocket at a certain time.
3. It discusses using higher order polynomials for interpolation, providing another example that calculates velocity using quadratic and cubic polynomials.
1) Ordinary differential equations relate a dependent variable to one or more independent variables by means of differential coefficients. They can be classified based on order, degree, whether they are linear or non-linear, and type (exact, separable variables, homogeneous).
2) First order differential equations can sometimes be solved by separation of variables, or by finding an integrating factor. Homogeneous equations can be transformed by substitution.
3) Second order linear differential equations can be reduced to a system of two first order equations. The complementary function and particular solutions combine to form the general solution. Unequal or equal roots of the characteristic equation determine the form of the complementary function.
An ellipse is defined algebraically as the set of all points where the sum of the distances to two fixed points (the foci) is a constant. Geometrically, an ellipse can be constructed by stretching a circle: using a piece of string fixed at both ends (the foci) and tracing the path of a pencil as it is moved around so that the total length of string remains constant.
The standard equation of an ellipse is (x-h)2/a2 + (y-k)2/b2 = 1, where (h,k) is the center and a and b are the lengths of the semi-major and semi-minor axes. To graph an ellipse, one plots
1. The rational function f(x) = 1/x^2 has a vertical asymptote at x = 2 because the denominator is 0 at that point.
2. As x values approach 2 from either side, y values approach positive or negative infinity, respectively.
3. The graph gets closer and closer to the vertical line x = 2 but never touches it. This line is called a vertical asymptote.
4. The graph also has a horizontal asymptote at y = 0, as y values approach 0 as x values increase or decrease indefinitely.
The document discusses closures of relations, including reflexive closure and symmetric closure. It provides definitions and theorems related to closures. It also uses an example to illustrate finding the reflexive closure and symmetric closure of a relation. Additionally, it covers topics like paths in directed graphs, shortest paths, and transitive closure. It includes an example of calculating the transitive closure of a relation by finding its zero-one matrix.
Lesson 26: The Fundamental Theorem of Calculus (slides)
The document discusses the Fundamental Theorem of Calculus, which has two parts. The first part states that if a function f is continuous on an interval, then the derivative of the integral of f is equal to f. This is proven using Riemann sums. The second part relates the integral of a function f to the integral of its derivative F'. Examples are provided to illustrate how the area under a curve relates to these concepts.
This document discusses several numerical analysis methods for finding roots of equations or solving systems of equations. It describes the bisection method for finding roots of continuous functions, the method of false positions for approximating roots between two values with opposite signs of a function, Gauss elimination for transforming a system of equations into triangular form, Gauss-Jordan method which further eliminates variables in equations below, and iterative methods which find solutions through successive approximations rather than direct computation.
This document defines metric spaces and discusses their basic properties. It begins by defining what a metric is and what constitutes a metric space. It provides some basic examples of metrics, such as the discrete metric and p-norm metrics. It then discusses metric topologies, defining open and closed balls and showing that the collection of open sets forms a topology. It also introduces the concept of topologically equivalent metrics.
1) The document defines partial derivatives of functions of multiple variables and discusses notation for partial derivatives.
2) It describes calculating a partial derivative by treating all other variables as constants and taking the ordinary derivative with respect to the variable of interest.
3) Higher order partial derivatives are discussed, which are partial derivatives of previously obtained partial derivatives. Schwartz' theorem states that for functions of two variables, mixed partial derivatives are equal if one of them exists and is continuous.
This document defines key concepts related to straight lines, including their various forms of equations, slope, intercepts, and how to calculate them. It discusses the general, standard, point-slope, and intercept forms of linear equations. It also explains how to find the slope between two points using the slope formula, and how to determine the x-intercept and y-intercept from a line's equation. Examples are provided to illustrate these concepts.
The document discusses inverse functions, including:
- An inverse function undoes the output of the original function by relating the input and output variables.
- For a function to have an inverse, it must be one-to-one so that each output is paired with a unique input.
- To find the inverse of a function, swap the input and output variables and isolate the new output variable.
Integration is used in physics to determine rates of change and distances given velocities. Numerical integration is required when the antiderivative is unknown. It involves approximating the definite integral of a function as the area under its curve between bounds. The Trapezoidal Rule approximates this area using straight lines between points, while Simpson's Rule uses quadratic or cubic functions, achieving greater accuracy with fewer points. Both methods involve dividing the area into strips and summing their widths multiplied by the function values at strip points.
This geometry lesson covers properties of isosceles and equilateral triangles. It defines key terms like base angles theorem and equilateral triangle corollary. Examples are provided to find missing angle and side measures in various triangles. Students are guided through practice problems to apply the concepts before independent practice questions to find values of variables and perimeters of triangles.
The derivative of a composition of functions is the product of the derivatives of those functions. This rule is important because compositions are so powerful.
The document discusses limits and the limit laws. It introduces the concept of a limit using an "error-tolerance" game. It then proves some basic limits, such as the limit of x as x approaches a equals a, and the limit of a constant c equals c. It also proves the limit laws, such as the fact that limits can be combined using arithmetic operations and the rules for limits of quotients and roots.
This document provides an outline for a calculus lecture on basic differentiation rules. It includes objectives to understand key rules like the constant multiple rule, sum rule, and derivatives of sine and cosine. Examples are worked through to find the derivatives of functions like squaring, cubing, square root, and cube root using the definition of the derivative. Graphs and properties of derived functions are also discussed.
Many functions in nature are described as the rate of change of another function. The concept is called the derivative. Algebraically, the process of finding the derivative involves a limit of difference quotients.
Many problems in nature are expressible in terms of a certain differential equation that has a solution in terms of exponential functions. We look at the equation in general and some fun applications, including radioactivity, cooling, and interest.
Lesson 20: Derivatives and the Shapes of Curves (slides)
This document contains lecture notes on derivatives and the shapes of curves from a Calculus I class taught by Professor Matthew Leingang at New York University. The notes cover using derivatives to determine the intervals where a function is increasing or decreasing, classifying critical points as maxima or minima, using the second derivative to determine concavity, and applying the first and second derivative tests. Examples are provided to illustrate finding intervals of monotonicity for various functions.
There are various reasons why we would want to find the extreme (maximum and minimum values) of a function. Fermat's Theorem tells us we can find local extreme points by looking at critical points. This process is known as the Closed Interval Method.
The Taylor series provides a means to approximate a function value at one point based on the function value and its derivatives at another known point. It states that any smooth function can be approximated as a polynomial. The Taylor series expansion allows estimating the value of a function like x^100 at a point like x=20 by using the known value and derivatives of the function at another point, like x=1. Increasing the order of the Taylor series approximation or decreasing the step size between points improves the accuracy of the approximation.
Lesson 12: Linear Approximations and Differentials (slides)
The line tangent to a curve is also the line which best "fits" the curve near that point. So derivatives can be used for approximating complicated functions with simple linear ones. Differentials are another set of notation for the same problem.
The document discusses an introductory calculus class and provides announcements about homework due dates and a student survey. It also outlines guidelines for written homework assignments, the grading rubric, and examples of what to include and avoid in written work. The document aims to provide students information about course policies and expectations for written assignments.
The product rule is generally better because:
- It is more systematic and avoids mistakes from expanding products
- It works for any differentiable functions u and v, not just polynomials
- It provides insight into the structure of the derivative that direct computation does not
So in this example, using the product rule is preferable to direct multiplication.
1) The document provides an overview of continuity, including defining continuity as a function having a limit equal to its value at a point.
2) It discusses several theorems related to continuity, such as the sum of continuous functions being continuous and various trigonometric, exponential, and logarithmic functions being continuous on their domains.
3) The document also covers inverse trigonometric functions and their domains of continuity.
Using implicit differentiation we can treat relations which are not quite functions like they were functions. In particular, we can find the slopes of lines tangent to curves which are not graphs of functions.
We cover the inverses to the trigonometric functions sine, cosine, tangent, cotangent, secant, cosecant, and their derivatives. The remarkable fact is that although these functions and their inverses are transcendental (complicated) functions, the derivatives are algebraic functions. Also, we meet my all-time favorite function: arctan.
The document discusses curve sketching of functions by analyzing their derivatives. It provides:
1) A checklist for graphing a function which involves finding where the function is positive/negative/zero, its monotonicity from the first derivative, and concavity from the second derivative.
2) An example of graphing the cubic function f(x) = 2x^3 - 3x^2 - 12x through analyzing its derivatives.
3) Explanations of the increasing/decreasing test and concavity test to determine monotonicity and concavity from a function's derivatives.
Lesson 2: A Catalog of Essential Functions (slides)
This document provides an overview of different types of functions including: linear, polynomial, rational, power, trigonometric, and exponential functions. It discusses representing functions verbally, numerically, visually, and symbolically. Key topics covered include transformations of functions through shifting graphs vertically and horizontally, as well as composing multiple functions.
This document discusses the mean value theorem and continuity in calculus. It defines Rolle's theorem, which states that if a function is continuous on a closed interval and differentiable on the open interval, and if the function is equal at the endpoints, then its derivative must be equal to zero for at least one value between the endpoints. It then uses Rolle's theorem to prove the mean value theorem, which states that the rate of change of a function over an interval is equal to the derivative of the function at some value between the endpoints. Finally, it introduces the Cauchy mean value theorem, which relates the rates of change of two functions over an interval to their derivatives at some interior point.
The document is a lecture on derivatives and the shapes of curves. It covers the mean value theorem, testing for monotonicity using the first derivative test, and finding intervals of monotonicity. It also discusses concavity and the second derivative test. Examples are provided to demonstrate how to find the intervals where a function is increasing or decreasing using the first derivative test.
We discuss the ideas of monotonicity (increasing or decreasing) and concavity (up or down) of a function. Because of the Mean Value Theorem, we can determine these characteristics using derivatives.
The Mean Value Theorem is the most important theorem in calculus! It allows us to infer information about a function from information about its derivative. Such as: a function whose derivative is zero must be a constant function.
1. Rolle's theorem states that if a function f(x) is continuous on the closed interval [a,b] and differentiable on the open interval (a,b), and f(a) = f(b), then there exists at least one number c in (a,b) where the derivative f'(c) = 0.
2. The mean value theorem states that if a function f(x) is continuous on a closed interval [a,b] and differentiable on the open interval (a,b), there exists a number c in (a,b) such that f'(c) = (f(b) - f(a))/(b - a).
Benginning Calculus Lecture notes 2 - limits and continuitybasyirstar
This document discusses limits and continuity in calculus. It begins by defining limits and providing examples of computing limits of functions. It then covers one-sided limits, properties of limits, and using direct substitution to evaluate limits. The document also discusses limits of trigonometric functions and infinite limits. The overall goal is to determine the existence of limits, compute limits, understand continuity of functions, and connect the ideas of limits and continuity.
1. The chain rule describes how to take the derivative of a function composed of other functions. It states that if z = f(x, y) and x and y are functions of t, then the derivative of z with respect to t is the sum of the partial derivatives multiplied by the derivatives of x and y with respect to t.
2. The chain rule is applied to find the derivative of two example functions, w = xy and w = xy + z, with respect to t along given paths for x, y, and z in terms of t.
3. The chain rule is generalized to the case of a function u of n variables, where each variable is a function of m other variables
The document introduces approximations of the area under a curve using Riemann sums with rectangles. It explains left and right Riemann sums, showing how to calculate them by dividing the area into equal subintervals and determining the height of each rectangle. While Riemann sums provide approximations, taking the widths of the subintervals to zero provides the exact area under a curve, as shown in a video clip about the concept. Riemann sums have applications in economics for determining consumer surplus and in science for modeling phenomena like blood flow.
Rational Zeros and Decarte's Rule of Signsswartzje
The Rational Zero Theorem provides a method to determine all possible rational zeros of a polynomial function. It states that if p/q is a rational zero, then p is a factor of the constant term and q is a factor of the leading coefficient. Descartes' Rule of Signs can be used to determine the maximum number of positive and negative real zeros by counting the variations in sign of the polynomial function and its substitution of -x. It provides bounds on the number of positive and negative real zeros that are either the number of variations in sign or less by an even integer. The example demonstrates applying these methods to determine all 16 possible rational zeros and the bounds of 0 positive and either 3 or 1 negative real zeros for the given polynomial.
critical points/ stationary points , turning points,Increasing, decreasing functions, absolute maxima & Minima, Local Maxima & Minima , convex upward & convex downward - first & second derivative tests.
This document discusses finding the maximum and minimum values of functions, as well as points of inflection. It provides instructions on how to find the coordinates of turning points by setting the derivative of the function equal to zero and solving. It also discusses how to determine if a turning point is a maximum or minimum by taking the second derivative and checking if it is positive or negative. The document concludes by giving examples of how to apply these concepts to optimization word problems involving areas, volumes, or other quantities that need to be maximized or minimized under certain constraints.
The document provides information about Lagrangian interpolation, including:
1. It introduces Lagrangian interpolation as a method to find the value of a function at a discrete point using a polynomial that passes through known data points.
2. It gives the formula for the Lagrangian interpolating polynomial and provides an example of using it to find the velocity of a rocket at a certain time.
3. It discusses using higher order polynomials for interpolation, providing another example that calculates velocity using quadratic and cubic polynomials.
1) Ordinary differential equations relate a dependent variable to one or more independent variables by means of differential coefficients. They can be classified based on order, degree, whether they are linear or non-linear, and type (exact, separable variables, homogeneous).
2) First order differential equations can sometimes be solved by separation of variables, or by finding an integrating factor. Homogeneous equations can be transformed by substitution.
3) Second order linear differential equations can be reduced to a system of two first order equations. The complementary function and particular solutions combine to form the general solution. Unequal or equal roots of the characteristic equation determine the form of the complementary function.
An ellipse is defined algebraically as the set of all points where the sum of the distances to two fixed points (the foci) is a constant. Geometrically, an ellipse can be constructed by stretching a circle: using a piece of string fixed at both ends (the foci) and tracing the path of a pencil as it is moved around so that the total length of string remains constant.
The standard equation of an ellipse is (x-h)2/a2 + (y-k)2/b2 = 1, where (h,k) is the center and a and b are the lengths of the semi-major and semi-minor axes. To graph an ellipse, one plots
1. The rational function f(x) = 1/x^2 has a vertical asymptote at x = 2 because the denominator is 0 at that point.
2. As x values approach 2 from either side, y values approach positive or negative infinity, respectively.
3. The graph gets closer and closer to the vertical line x = 2 but never touches it. This line is called a vertical asymptote.
4. The graph also has a horizontal asymptote at y = 0, as y values approach 0 as x values increase or decrease indefinitely.
The document discusses closures of relations, including reflexive closure and symmetric closure. It provides definitions and theorems related to closures. It also uses an example to illustrate finding the reflexive closure and symmetric closure of a relation. Additionally, it covers topics like paths in directed graphs, shortest paths, and transitive closure. It includes an example of calculating the transitive closure of a relation by finding its zero-one matrix.
Lesson 26: The Fundamental Theorem of Calculus (slides)Matthew Leingang
The document discusses the Fundamental Theorem of Calculus, which has two parts. The first part states that if a function f is continuous on an interval, then the derivative of the integral of f is equal to f. This is proven using Riemann sums. The second part relates the integral of a function f to the integral of its derivative F'. Examples are provided to illustrate how the area under a curve relates to these concepts.
This document discusses several numerical analysis methods for finding roots of equations or solving systems of equations. It describes the bisection method for finding roots of continuous functions, the method of false positions for approximating roots between two values with opposite signs of a function, Gauss elimination for transforming a system of equations into triangular form, Gauss-Jordan method which further eliminates variables in equations below, and iterative methods which find solutions through successive approximations rather than direct computation.
This document defines metric spaces and discusses their basic properties. It begins by defining what a metric is and what constitutes a metric space. It provides some basic examples of metrics, such as the discrete metric and p-norm metrics. It then discusses metric topologies, defining open and closed balls and showing that the collection of open sets forms a topology. It also introduces the concept of topologically equivalent metrics.
1) The document defines partial derivatives of functions of multiple variables and discusses notation for partial derivatives.
2) It describes calculating a partial derivative by treating all other variables as constants and taking the ordinary derivative with respect to the variable of interest.
3) Higher order partial derivatives are discussed, which are partial derivatives of previously obtained partial derivatives. Schwartz' theorem states that for functions of two variables, mixed partial derivatives are equal if one of them exists and is continuous.
This document defines key concepts related to straight lines, including their various forms of equations, slope, intercepts, and how to calculate them. It discusses the general, standard, point-slope, and intercept forms of linear equations. It also explains how to find the slope between two points using the slope formula, and how to determine the x-intercept and y-intercept from a line's equation. Examples are provided to illustrate these concepts.
The document discusses inverse functions, including:
- An inverse function undoes the output of the original function by relating the input and output variables.
- For a function to have an inverse, it must be one-to-one so that each output is paired with a unique input.
- To find the inverse of a function, swap the input and output variables and isolate the new output variable.
Integration is used in physics to determine rates of change and distances given velocities. Numerical integration is required when the antiderivative is unknown. It involves approximating the definite integral of a function as the area under its curve between bounds. The Trapezoidal Rule approximates this area using straight lines between points, while Simpson's Rule uses quadratic or cubic functions, achieving greater accuracy with fewer points. Both methods involve dividing the area into strips and summing their widths multiplied by the function values at strip points.
This geometry lesson covers properties of isosceles and equilateral triangles. It defines key terms like base angles theorem and equilateral triangle corollary. Examples are provided to find missing angle and side measures in various triangles. Students are guided through practice problems to apply the concepts before independent practice questions to find values of variables and perimeters of triangles.
The derivative of a composition of functions is the product of the derivatives of those functions. This rule is important because compositions are so powerful.
The document discusses limits and the limit laws. It introduces the concept of a limit using an "error-tolerance" game. It then proves some basic limits, such as the limit of x as x approaches a equals a, and the limit of a constant c equals c. It also proves the limit laws, such as the fact that limits can be combined using arithmetic operations and the rules for limits of quotients and roots.
This document provides an outline for a calculus lecture on basic differentiation rules. It includes objectives to understand key rules like the constant multiple rule, sum rule, and derivatives of sine and cosine. Examples are worked through to find the derivatives of functions like squaring, cubing, square root, and cube root using the definition of the derivative. Graphs and properties of derived functions are also discussed.
Many functions in nature are described as the rate of change of another function. The concept is called the derivative. Algebraically, the process of finding the derivative involves a limit of difference quotients.
Lesson 15: Exponential Growth and Decay (slides)Matthew Leingang
Many problems in nature are expressible in terms of a certain differential equation that has a solution in terms of exponential functions. We look at the equation in general and some fun applications, including radioactivity, cooling, and interest.
Lesson 20: Derivatives and the Shapes of Curves (slides)Matthew Leingang
This document contains lecture notes on derivatives and the shapes of curves from a Calculus I class taught by Professor Matthew Leingang at New York University. The notes cover using derivatives to determine the intervals where a function is increasing or decreasing, classifying critical points as maxima or minima, using the second derivative to determine concavity, and applying the first and second derivative tests. Examples are provided to illustrate finding intervals of monotonicity for various functions.
There are various reasons why we would want to find the extreme (maximum and minimum values) of a function. Fermat's Theorem tells us we can find local extreme points by looking at critical points. This process is known as the Closed Interval Method.
The Taylor series provides a means to approximate a function value at one point based on the function value and its derivatives at another known point. It states that any smooth function can be approximated as a polynomial. The Taylor series expansion allows estimating the value of a function like x^100 at a point like x=20 by using the known value and derivatives of the function at another point, like x=1. Increasing the order of the Taylor series approximation or decreasing the step size between points improves the accuracy of the approximation.
Lesson 12: Linear Approximations and Differentials (slides)Matthew Leingang
The line tangent to a curve is also the line which best "fits" the curve near that point. So derivatives can be used for approximating complicated functions with simple linear ones. Differentials are another set of notation for the same problem.
The document discusses an introductory calculus class and provides announcements about homework due dates and a student survey. It also outlines guidelines for written homework assignments, the grading rubric, and examples of what to include and avoid in written work. The document aims to provide students information about course policies and expectations for written assignments.
Lesson 9: The Product and Quotient Rules (slides)Matthew Leingang
The product rule is generally better because:
- It is more systematic and avoids mistakes from expanding products
- It works for any differentiable functions u and v, not just polynomials
- It provides insight into the structure of the derivative that direct computation does not
So in this example, using the product rule is preferable to direct multiplication.
1) The document provides an overview of continuity, including defining continuity as a function having a limit equal to its value at a point.
2) It discusses several theorems related to continuity, such as the sum of continuous functions being continuous and various trigonometric, exponential, and logarithmic functions being continuous on their domains.
3) The document also covers inverse trigonometric functions and their domains of continuity.
Using implicit differentiation we can treat relations which are not quite functions like they were functions. In particular, we can find the slopes of lines tangent to curves which are not graphs of functions.
We cover the inverses to the trigonometric functions sine, cosine, tangent, cotangent, secant, cosecant, and their derivatives. The remarkable fact is that although these functions and their inverses are transcendental (complicated) functions, the derivatives are algebraic functions. Also, we meet my all-time favorite function: arctan.
The document discusses curve sketching of functions by analyzing their derivatives. It provides:
1) A checklist for graphing a function which involves finding where the function is positive/negative/zero, its monotonicity from the first derivative, and concavity from the second derivative.
2) An example of graphing the cubic function f(x) = 2x^3 - 3x^2 - 12x through analyzing its derivatives.
3) Explanations of the increasing/decreasing test and concavity test to determine monotonicity and concavity from a function's derivatives.
Lesson 2: A Catalog of Essential Functions (slides)Matthew Leingang
This document provides an overview of different types of functions including: linear, polynomial, rational, power, trigonometric, and exponential functions. It discusses representing functions verbally, numerically, visually, and symbolically. Key topics covered include transformations of functions through shifting graphs vertically and horizontally, as well as composing multiple functions.
This document discusses the mean value theorem and continuity in calculus. It defines Rolle's theorem, which states that if a function is continuous on a closed interval and differentiable on the open interval, and if the function is equal at the endpoints, then its derivative must be equal to zero for at least one value between the endpoints. It then uses Rolle's theorem to prove the mean value theorem, which states that the rate of change of a function over an interval is equal to the derivative of the function at some value between the endpoints. Finally, it introduces the Cauchy mean value theorem, which relates the rates of change of two functions over an interval to their derivatives at some interior point.
The document is a lecture on derivatives and the shapes of curves. It covers the mean value theorem, testing for monotonicity using the first derivative test, and finding intervals of monotonicity. It also discusses concavity and the second derivative test. Examples are provided to demonstrate how to find the intervals where a function is increasing or decreasing using the first derivative test.
We discuss the ideas of monotonicity (increasing or decreasing) and concavity (up or down) of a function. Because of the Mean Value Theorem, we can determine these characteristics using derivatives.
The Mean Value Theorem is the most important theorem in calculus! It allows us to infer information about a function from information about its derivative. Such as: a function whose derivative is zero must be a constant function.
1. Rolle's theorem states that if a function f(x) is continuous on the closed interval [a,b] and differentiable on the open interval (a,b), and f(a) = f(b), then there exists at least one number c in (a,b) where the derivative f'(c) = 0.
2. The mean value theorem states that if a function f(x) is continuous on a closed interval [a,b] and differentiable on the open interval (a,b), there exists a number c in (a,b) such that f'(c) = (f(b) - f(a))/(b - a).
The document summarizes the Mean Value Theorem and Rolle's Theorem from calculus. The Mean Value Theorem states that for a differentiable function over a closed interval, there exists a point in the interval where the slope of the tangent line equals the average rate of change over the interval. Rolle's Theorem is a specific case of the Mean Value Theorem where the function value is equal at the endpoints of the interval. An example is provided to check if a function satisfies the hypotheses of Rolle's Theorem over an interval.
Rolle's theorem states that if a function is continuous on a closed interval and differentiable on the open interval with equal values at the endpoints, then the derivative is 0 for at least one value in the interval. The mean value theorems - Lagrange's and Cauchy's - generalize this idea, relating the average rate of change over an interval to the instantaneous rate at a point within the interval. Examples are provided to illustrate the theorems and exceptions that can occur when their conditions are not fully met.
The Mean Value Theorem is the most important theorem in calculus! It allows us to infer information about a function from information about its derivative. Such as: a function whose derivative is zero must be a constant function.
Explore the fundamental principles of the Mean Value Theorem and Rolle’s Theorem in this detailed guide. Learn about their key concepts, practical applications, and step-by-step examples to enhance your understanding of calculus. Ideal for students and math enthusiasts aiming to master these essential theorems.
This document covers key concepts in calculus including:
1) Approximating changes in a function using derivatives, finding local linearizations.
2) Identifying local extrema, maxima and minima, of a function using first derivatives.
3) Defining critical points as points where the derivative is zero or undefined.
4) Relating properties of the first and second derivatives to characteristics of the original function like concavity, inflection points, and local extrema.
This document discusses Rolle's theorem and the mean value theorem. It provides the definitions and formulas for each theorem. It then gives examples of applying each theorem to find values of c where a derivative is equal to zero or a tangent line is parallel to a secant line. Rolle's theorem examples find values of c where the derivative of a function over an interval is zero. The mean value theorem examples find values of c where the slope of a tangent line equals the slope of a secant line over an interval.
The document discusses the Mean Value Theorem and its applications. It begins by introducing Rolle's Theorem, which states that if a function f is continuous on a closed interval [a,b] and differentiable on the open interval (a,b), and if f(a) = f(b), then there exists a number c in (a,b) where the derivative f'(c) is equal to 0. It then proves the Mean Value Theorem, which states that if a function f is continuous on [a,b] and differentiable on (a,b), then there exists a number c in (a,b) where the instantaneous rate of change of f at c is equal to the average rate
The Mean Value Theorem is the most important theorem in calculus! It allows us to infer information about a function from information about its derivative. Such as: a function whose derivative is zero must be a constant function.
This document summarizes a calculus lecture on the Mean Value Theorem. It begins with announcements about exams and assignments. It then outlines the topics to be covered: Rolle's Theorem and the Mean Value Theorem, applications of the MVT, and why the MVT is important. It provides heuristic motivations and mathematical statements of Rolle's Theorem and the Mean Value Theorem. It also includes a proof of the Mean Value Theorem using Rolle's Theorem.
This document is the notes from a Calculus I class at New York University covering Section 4.2 on the Mean Value Theorem. The notes include objectives, an outline, explanations of Rolle's Theorem and the Mean Value Theorem, examples of using the theorems, and a food for thought question. The key points are that Rolle's Theorem states that if a function is continuous on an interval and differentiable inside the interval, and the function values at the endpoints are equal, then there exists a point in the interior where the derivative is 0. The Mean Value Theorem similarly states that if a function is continuous on an interval and differentiable inside, there exists a point where the average rate of change equals the instantaneous rate of
Mean Value Theorem explained with examples.pptxvandijkvvd4
The Mean Value Theorem (MVT) is a crucial concept in calculus, connecting the average rate of change of a function to its instantaneous rate of change. It's a fundamental theorem that holds a significant place in calculus and has far-reaching implications across various mathematical fields. Exploring it through 3000 alphabets involves diving into its core principles, applications, and significance.
At its heart, the Mean Value Theorem asserts that if a function is continuous on a closed interval and differentiable on the open interval, there exists at least one point within that interval where the instantaneous rate of change (the derivative) equals the average rate of change of the function over that interval.
Geometrically, MVT can be visualized as a tangent line parallel to a secant line at a certain point within the function, signifying the equality between the average and instantaneous rates of change.
Understanding MVT involves grasping its conditions and implications. For a function
�
(
�
)
f(x), the prerequisites for applying MVT are continuity and differentiability within the specified interval
[
�
,
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]
[a,b].
The theorem's application extends to various contexts in mathematics, science, and economics. It's utilized to prove the existence of solutions to equations, establish bounds for functions, and analyze behavior in optimization problems.
MVT plays a pivotal role in other fundamental theorems of calculus like the Fundamental Theorem of Calculus, aiding in the development of integral calculus and its applications in areas such as physics, engineering, and economics.
Beyond its practical applications, the Mean Value Theorem's elegance lies in its capacity to capture the essence of rates of change, providing a bridge between local and global behavior of functions.
Mathematicians and scientists rely on MVT to understand and model real-world phenomena, utilizing its principles to analyze trends, make predictions, and solve problems across diverse disciplines.
In essence, the Mean Value Theorem stands as a cornerstone of calculus, fostering a deeper comprehension of the relationship between a function and its derivatives while serving as a powerful tool in mathematical analysis and problem-solving.
The Mean Value Theorem (MVT) in calculus asserts that for a continuous and differentiable function on a closed interval, there exists at least one point within that interval where the derivative (instantaneous rate of change) of the function equals the average rate of change of the function over that interval. It's a fundamental concept connecting the behavior of functions locally and globally, pivotal in calculus, and extensively applied in various fields like physics, engineering, and economics. MVT's essence lies in relating the function's behavior at specific points to its overall behavior, aiding in problem-solving, equation-solving, and understanding rates of change in real-world scenarios.
MVT relates function's average to in
The Mean Value Theorem states that if a function is continuous on a closed interval and differentiable on the open interval, then there exists a point within the interval where the slope of the tangent line equals the derivative of the function at that point. Rolle's Theorem is a specific case where the function is equal at the endpoints of the interval, and thus there must exist a point where the derivative is 0. The examples show numbers that satisfy the Mean Value Theorem within given intervals.
Rolle's Theorem states that if a function f(x) is continuous on a closed interval [a,b] and differentiable on the open interval (a,b), where f(a) = f(b), then there exists at least one number c in the open interval (a,b) where the derivative f'(c) is equal to 0. The document provides an example of applying Rolle's Theorem to the polynomial function f(x) = x^2 - 2.5x + 1.5 on the interval [1,2], showing that the derivative is 0 at x = 1.5.
The document provides a review outline for Math 1a Midterm II covering topics including: differentiation using product, quotient, and chain rules; implicit differentiation; logarithmic differentiation; applications such as related rates and optimization; and the shape of curves including the mean value theorem and extreme value theorem. It also lists learning objectives and provides details on key concepts like L'Hopital's rule and the closed interval method for finding extrema.
Similar to Lesson 19: The Mean Value Theorem (slides) (20)
This document provides guidance on developing effective lesson plans for calculus instructors. It recommends starting by defining specific learning objectives and assessments. Examples should be chosen carefully to illustrate concepts and engage students at a variety of levels. The lesson plan should include an introductory problem, definitions, theorems, examples, and group work. Timing for each section should be estimated. After teaching, the lesson can be improved by analyzing what was effective and what needs adjustment for the next time. Advanced preparation is key to looking prepared and ensuring students learn.
Streamlining assessment, feedback, and archival with auto-multiple-choiceMatthew Leingang
Auto-multiple-choice (AMC) is an open-source optical mark recognition software package built with Perl, LaTeX, XML, and sqlite. I use it for all my in-class quizzes and exams. Unique papers are created for each student, fixed-response items are scored automatically, and free-response problems, after manual scoring, have marks recorded in the same process. In the first part of the talk I will discuss AMC’s many features and why I feel it’s ideal for a mathematics course. My contributions to the AMC workflow include some scripts designed to automate the process of returning scored papers
back to students electronically. AMC provides an email gateway, but I have written programs to return graded papers via the DAV protocol to student’s dropboxes on our (Sakai) learning management systems. I will also show how graded papers can be archived, with appropriate metadata tags, into an Evernote notebook.
This document discusses electronic grading of paper assessments using PDF forms. Key points include:
- Various tools for creating fillable PDF forms using LaTeX packages or desktop software.
- Methods for stamping completed forms onto scanned documents including using pdftk or overlaying in TikZ.
- Options for grading on tablets or desktops including GoodReader, PDFExpert, Adobe Acrobat.
- Extracting data from completed forms can be done in Adobe Acrobat or via command line with pdftk.
Integration by substitution is the chain rule in reverse.
NOTE: the final location is section specific. Section 1 (morning) is in SILV 703, Section 11 (afternoon) is in CANT 200
Lesson 26: The Fundamental Theorem of Calculus (slides)Matthew Leingang
g(x) represents the area under the curve of f(t) between 0 and x.
.
x
What can you say about g? 2 4 6 8 10f
The First Fundamental Theorem of Calculus
Theorem (First Fundamental Theorem of Calculus)
Let f be a con nuous func on on [a, b]. Define the func on F on [a, b] by
∫ x
F(x) = f(t) dt
a
Then F is con nuous on [a, b] and differentiable on (a, b) and for all x in (a, b),
F′(x
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This document contains lecture notes on integration by substitution from a Calculus I class. It introduces the technique of substitution for both indefinite and definite integrals. For indefinite integrals, the substitution rule is presented, along with examples of using substitutions to evaluate integrals involving polynomials, trigonometric, exponential, and other functions. For definite integrals, the substitution rule is extended and examples are worked through both with and without first finding the indefinite integral. The document emphasizes that substitution often simplifies integrals and makes them easier to evaluate.
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1) The document discusses lecture notes on Section 5.4: The Fundamental Theorem of Calculus from a Calculus I course. 2) It covers stating and explaining the Fundamental Theorems of Calculus and using the first fundamental theorem to find derivatives of functions defined by integrals. 3) The lecture outlines the first fundamental theorem, which relates differentiation and integration, and gives examples of applying it.
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Uncountably many problems in life and nature can be expressed in terms of an optimization principle. We look at the process and find a few good examples.
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There are various reasons why we would want to find the extreme (maximum and minimum values) of a function. Fermat's Theorem tells us we can find local extreme points by looking at critical points. This process is known as the Closed Interval Method.
Lesson 17: Indeterminate forms and l'Hôpital's Rule (handout)
Lesson 19: The Mean Value Theorem (slides)
1. Sec on 4.2
The Mean Value Theorem
V63.0121.011: Calculus I
Professor Ma hew Leingang
New York University
April 6, 2011
.
2. Announcements
Quiz 4 on Sec ons 3.3,
3.4, 3.5, and 3.7 next
week (April 14/15)
Quiz 5 on Sec ons
4.1–4.4 April 28/29
Final Exam Thursday May
12, 2:00–3:50pm
3. Courant Lecture tomorrow
Persi Diaconis (Stanford)
“The Search for Randomness”
(General Audience Lecture)
Thursday, April 7, 2011, 3:30pm
Warren Weaver Hall, room 109
Recep on to follow
Visit http://cims.nyu.edu/ for details
and to RSVP
4. Objectives
Understand and be able
to explain the statement
of Rolle’s Theorem.
Understand and be able
to explain the statement
of the Mean Value
Theorem.
5. Outline
Rolle’s Theorem
The Mean Value Theorem
Applica ons
Why the MVT is the MITC
Func ons with deriva ves that are zero
MVT and differen ability
6. Heuristic Motivation for Rolle’s Theorem
If you bike up a hill, then back down, at some point your eleva on
was sta onary.
.
Image credit: SpringSun
7. Mathematical Statement of Rolle’s
Theorem
Theorem (Rolle’s Theorem)
Let f be con nuous on [a, b]
and differen able on (a, b).
Suppose f(a) = f(b). Then
there exists a point c in
(a, b) such that f′ (c) = 0. .
a b
8. Mathematical Statement of Rolle’s
Theorem
Theorem (Rolle’s Theorem)
c
Let f be con nuous on [a, b]
and differen able on (a, b).
Suppose f(a) = f(b). Then
there exists a point c in
(a, b) such that f′ (c) = 0. .
a b
9. Flowchart proof of Rolle’s Theorem
endpoints
Let c be
. Let d be
. . .
are max
the max pt the min pt
and min
f is
is c.an is d. an. .
yes yes constant
endpoint? endpoint?
on [a, b]
no no
′ ′ f′ (x) .≡ 0
f (c) .= 0 f (d) .= 0
on (a, b)
10. Outline
Rolle’s Theorem
The Mean Value Theorem
Applica ons
Why the MVT is the MITC
Func ons with deriva ves that are zero
MVT and differen ability
11. Heuristic Motivation for The Mean Value Theorem
If you drive between points A and B, at some me your speedometer
reading was the same as your average speed over the drive.
.
Image credit: ClintJCL
12. The Mean Value Theorem
Theorem (The Mean Value Theorem)
Let f be con nuous on
[a, b] and differen able on
(a, b). Then there exists a
point c in (a, b) such that
f(b) − f(a) b
= f′ (c). .
b−a a
13. The Mean Value Theorem
Theorem (The Mean Value Theorem)
Let f be con nuous on
[a, b] and differen able on
(a, b). Then there exists a
point c in (a, b) such that
f(b) − f(a) b
= f′ (c). .
b−a a
14. The Mean Value Theorem
Theorem (The Mean Value Theorem)
Let f be con nuous on c
[a, b] and differen able on
(a, b). Then there exists a
point c in (a, b) such that
f(b) − f(a) b
= f′ (c). .
b−a a
15. Rolle vs. MVT
f(b) − f(a)
f′ (c) = 0 = f′ (c)
b−a
c c
b
. .
a b a
16. Rolle vs. MVT
f(b) − f(a)
f′ (c) = 0 = f′ (c)
b−a
c c
b
. .
a b a
If the x-axis is skewed the pictures look the same.
17. Proof of the Mean Value Theorem
Proof.
The line connec ng (a, f(a)) and (b, f(b)) has equa on
f(b) − f(a)
L(x) = f(a) + (x − a)
b−a
18. Proof of the Mean Value Theorem
Proof.
The line connec ng (a, f(a)) and (b, f(b)) has equa on
f(b) − f(a)
L(x) = f(a) + (x − a)
b−a
Apply Rolle’s Theorem to the func on
f(b) − f(a)
g(x) = f(x) − L(x) = f(x) − f(a) − (x − a).
b−a
19. Proof of the Mean Value Theorem
Proof.
The line connec ng (a, f(a)) and (b, f(b)) has equa on
f(b) − f(a)
L(x) = f(a) + (x − a)
b−a
Apply Rolle’s Theorem to the func on
f(b) − f(a)
g(x) = f(x) − L(x) = f(x) − f(a) − (x − a).
b−a
Then g is con nuous on [a, b] and differen able on (a, b) since f is.
20. Proof of the Mean Value Theorem
Proof.
The line connec ng (a, f(a)) and (b, f(b)) has equa on
f(b) − f(a)
L(x) = f(a) + (x − a)
b−a
Apply Rolle’s Theorem to the func on
f(b) − f(a)
g(x) = f(x) − L(x) = f(x) − f(a) − (x − a).
b−a
Then g is con nuous on [a, b] and differen able on (a, b) since f is.
Also g(a) = 0 and g(b) = 0 (check both).
21. Proof of the Mean Value Theorem
Proof.
f(b) − f(a)
g(x) = f(x) − L(x) = f(x) − f(a) − (x − a).
b−a
So by Rolle’s Theorem there exists a point c in (a, b) such that
f(b) − f(a)
0 = g′ (c) = f′ (c) − .
b−a
22. Using the MVT to count solutions
Example
Show that there is a unique solu on to the equa on x3 − x = 100 in the
interval [4, 5].
23. Using the MVT to count solutions
Example
Show that there is a unique solu on to the equa on x3 − x = 100 in the
interval [4, 5].
Solu on
By the Intermediate Value Theorem, the func on f(x) = x3 − x
must take the value 100 at some point on c in (4, 5).
24. Using the MVT to count solutions
Example
Show that there is a unique solu on to the equa on x3 − x = 100 in the
interval [4, 5].
Solu on
By the Intermediate Value Theorem, the func on f(x) = x3 − x
must take the value 100 at some point on c in (4, 5).
If there were two points c1 and c2 with f(c1 ) = f(c2 ) = 100,
then somewhere between them would be a point c3 between
them with f′ (c3 ) = 0.
25. Using the MVT to count solutions
Example
Show that there is a unique solu on to the equa on x3 − x = 100 in the
interval [4, 5].
Solu on
By the Intermediate Value Theorem, the func on f(x) = x3 − x
must take the value 100 at some point on c in (4, 5).
If there were two points c1 and c2 with f(c1 ) = f(c2 ) = 100,
then somewhere between them would be a point c3 between
them with f′ (c3 ) = 0.
However, f′ (x) = 3x2 − 1, which is posi ve all along (4, 5). So
this is impossible.
26. Using the MVT to estimate
Example
We know that |sin x| ≤ 1 for all x, and that sin x ≈ x for small x.
Show that |sin x| ≤ |x| for all x.
27. Using the MVT to estimate
Example
We know that |sin x| ≤ 1 for all x, and that sin x ≈ x for small x.
Show that |sin x| ≤ |x| for all x.
Solu on
Apply the MVT to the func on
f(t) = sin t on [0, x]. We get Since |cos(c)| ≤ 1, we get
sin x − sin 0 sin x
= cos(c) ≤ 1 =⇒ |sin x| ≤ |x|
x−0 x
for some c in (0, x).
28. Using the MVT to estimate II
Example
Let f be a differen able func on with f(1) = 3 and f′ (x) < 2 for all x
in [0, 5]. Could f(4) ≥ 9?
29. Using the MVT to estimate II
Solu on
By MVT
f(4) − f(1)
= f′ (c) < 2
4−1
for some c in (1, 4). Therefore
f(4) = f(1) + f′ (c)(3) < 3 + 2 · 3 = 9.
So no, it is impossible that f(4) ≥ 9.
30. Using the MVT to estimate II
Solu on
By MVT
y (4, 9)
f(4) − f(1)
= f′ (c) < 2 (4, f(4))
4−1
for some c in (1, 4). Therefore
f(4) = f(1) + f′ (c)(3) < 3 + 2 · 3 = 9. (1, 3)
So no, it is impossible that f(4) ≥ 9. . x
31. Food for Thought
Ques on
A driver travels along the New Jersey Turnpike using E-ZPass. The
system takes note of the me and place the driver enters and exits
the Turnpike. A week a er his trip, the driver gets a speeding cket
in the mail. Which of the following best describes the situa on?
(a) E-ZPass cannot prove that the driver was speeding
(b) E-ZPass can prove that the driver was speeding
(c) The driver’s actual maximum speed exceeds his cketed speed
(d) Both (b) and (c).
32. Food for Thought
Ques on
A driver travels along the New Jersey Turnpike using E-ZPass. The
system takes note of the me and place the driver enters and exits
the Turnpike. A week a er his trip, the driver gets a speeding cket
in the mail. Which of the following best describes the situa on?
(a) E-ZPass cannot prove that the driver was speeding
(b) E-ZPass can prove that the driver was speeding
(c) The driver’s actual maximum speed exceeds his cketed speed
(d) Both (b) and (c).
33. Outline
Rolle’s Theorem
The Mean Value Theorem
Applica ons
Why the MVT is the MITC
Func ons with deriva ves that are zero
MVT and differen ability
35. Functions with derivatives that are zero
Fact
If f is constant on (a, b), then f′ (x) = 0 on (a, b).
The limit of difference quo ents must be 0
The tangent line to a line is that line, and a constant func on’s
graph is a horizontal line, which has slope 0.
Implied by the power rule since c = cx0
37. Functions with derivatives that are zero
Ques on
If f′ (x) = 0 is f necessarily a constant func on?
It seems true
But so far no theorem (that we have proven) uses informa on
about the deriva ve of a func on to determine informa on
about the func on itself
38. Why the MVT is the MITC
(Most Important Theorem In Calculus!)
Theorem
Let f′ = 0 on an interval (a, b).
39. Why the MVT is the MITC
(Most Important Theorem In Calculus!)
Theorem
Let f′ = 0 on an interval (a, b). Then f is constant on (a, b).
40. Why the MVT is the MITC
(Most Important Theorem In Calculus!)
Theorem
Let f′ = 0 on an interval (a, b). Then f is constant on (a, b).
Proof.
Pick any points x and y in (a, b) with x < y. Then f is con nuous on
[x, y] and differen able on (x, y). By MVT there exists a point z in
(x, y) such that
f(y) − f(x)
= f′ (z) = 0.
y−x
So f(y) = f(x). Since this is true for all x and y in (a, b), then f is
constant.
41. Functions with the same derivative
Theorem
Suppose f and g are two differen able func ons on (a, b) with
f′ = g′ . Then f and g differ by a constant. That is, there exists a
constant C such that f(x) = g(x) + C.
42. Functions with the same derivative
Theorem
Suppose f and g are two differen able func ons on (a, b) with
f′ = g′ . Then f and g differ by a constant. That is, there exists a
constant C such that f(x) = g(x) + C.
Proof.
43. Functions with the same derivative
Theorem
Suppose f and g are two differen able func ons on (a, b) with
f′ = g′ . Then f and g differ by a constant. That is, there exists a
constant C such that f(x) = g(x) + C.
Proof.
Let h(x) = f(x) − g(x)
44. Functions with the same derivative
Theorem
Suppose f and g are two differen able func ons on (a, b) with
f′ = g′ . Then f and g differ by a constant. That is, there exists a
constant C such that f(x) = g(x) + C.
Proof.
Let h(x) = f(x) − g(x)
Then h′ (x) = f′ (x) − g′ (x) = 0 on (a, b)
45. Functions with the same derivative
Theorem
Suppose f and g are two differen able func ons on (a, b) with
f′ = g′ . Then f and g differ by a constant. That is, there exists a
constant C such that f(x) = g(x) + C.
Proof.
Let h(x) = f(x) − g(x)
Then h′ (x) = f′ (x) − g′ (x) = 0 on (a, b)
So h(x) = C, a constant
46. Functions with the same derivative
Theorem
Suppose f and g are two differen able func ons on (a, b) with
f′ = g′ . Then f and g differ by a constant. That is, there exists a
constant C such that f(x) = g(x) + C.
Proof.
Let h(x) = f(x) − g(x)
Then h′ (x) = f′ (x) − g′ (x) = 0 on (a, b)
So h(x) = C, a constant
This means f(x) − g(x) = C on (a, b)
48. MVT and differentiability
Example Solu on (from the defini on)
Let We have
{
−x if x ≤ 0 f(x) − f(0) −x
f(x) = lim− = lim− = −1
x2 if x ≥ 0 x→0 x−0 x→0 x
f(x) − f(0) x2
Is f differen able at 0? lim = lim+ = lim+ x = 0
x→0+ x−0 x→0 x x→0
Since these limits disagree, f is not
differen able at 0.
49. MVT and differentiability
Example Solu on (Sort of)
Let If x < 0, then f′ (x) = −1. If x > 0, then
{ f′ (x) = 2x. Since
−x if x ≤ 0
f(x) =
x2 if x ≥ 0 lim+ f′ (x) = 0 and lim− f′ (x) = −1,
x→0 x→0
Is f differen able at 0? the limit lim f′ (x) does not exist and so f is
x→0
not differen able at 0.
50. Why only “sort of”?
This solu on is valid but less f′ (x)
direct. y f(x)
We seem to be using the
following fact: If lim f′ (x) does
x→a
not exist, then f is not . x
differen able at a.
equivalently: If f is differen able
at a, then lim f′ (x) exists.
x→a
But this “fact” is not true!
51. Differentiable with discontinuous derivative
It is possible for a func on f to be differen able at a even if lim f′ (x)
x→a
does not exist.
Example
{
′ x2 sin(1/x) if x ̸= 0
Let f (x) = .
0 if x = 0
Then when x ̸= 0,
f′ (x) = 2x sin(1/x) + x2 cos(1/x)(−1/x2 ) = 2x sin(1/x) − cos(1/x),
which has no limit at 0.
52. Differentiable with discontinuous derivative
It is possible for a func on f to be differen able at a even if lim f′ (x)
x→a
does not exist.
Example
{
′ x2 sin(1/x) if x ̸= 0
Let f (x) = .
0 if x = 0
However,
′ f(x) − f(0) x2 sin(1/x)
f (0) = lim = lim = lim x sin(1/x) = 0
x→0 x−0 x→0 x x→0
So f′ (0) = 0. Hence f is differen able for all x, but f′ is not
con nuous at 0!
53. Differentiability FAIL
f(x) f′ (x)
. x . x
This func on is differen able But the deriva ve is not
at 0. con nuous at 0!
54. MVT to the rescue
Lemma
Suppose f is con nuous on [a, b] and lim+ f′ (x) = m. Then
x→a
f(x) − f(a)
lim+ = m.
x→a x−a
55. MVT to the rescue
Proof.
Choose x near a and greater than a. Then
f(x) − f(a)
= f′ (cx )
x−a
for some cx where a < cx < x. As x → a, cx → a as well, so:
f(x) − f(a)
lim+ = lim+ f′ (cx ) = lim+ f′ (x) = m.
x→a x−a x→a x→a
56. Using the MVT to find limits
Theorem
Suppose
lim f′ (x) = m1 and lim+ f′ (x) = m2
x→a− x→a
If m1 = m2 , then f is differen able at a. If m1 ̸= m2 , then f is not
differen able at a.
57. Using the MVT to find limits
Proof.
We know by the lemma that
f(x) − f(a)
lim− = lim− f′ (x)
x→a x−a x→a
f(x) − f(a)
lim+ = lim+ f′ (x)
x→a x−a x→a
The two-sided limit exists if (and only if) the two right-hand sides
agree.
58. Summary
Rolle’s Theorem: under suitable condi ons, func ons must
have cri cal points.
Mean Value Theorem: under suitable condi ons, func ons
must have an instantaneous rate of change equal to the
average rate of change.
A func on whose deriva ve is iden cally zero on an interval
must be constant on that interval.
E-ZPass is kinder than we realized.