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Ch. 3 - Derivatives
Briggs - Calculus: Early Transcendentals 3rd Edition
Briggs3rd EditionCalculus: Early TranscendentalsISBN: 9780136847243Not the one you use?Change textbook
Chapter 3, Problem 3.8.14a

13-26 Implicit differentiation Carry out the following steps.
a. Use implicit differentiation to find dy/dx.
x = e^y; (2, ln 2)

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Start by differentiating both sides of the equation with respect to x. The equation given is x = e^y.
Differentiate the left side: The derivative of x with respect to x is 1.
Differentiate the right side: Use the chain rule. The derivative of e^y with respect to y is e^y, and then multiply by dy/dx because of the chain rule. So, the derivative is e^y * (dy/dx).
Set the derivatives equal to each other: 1 = e^y * (dy/dx).
Solve for dy/dx by dividing both sides by e^y: dy/dx = 1/e^y. Substitute the point (2, ln 2) into the equation to find the specific value of dy/dx at that point.

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Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

Implicit Differentiation

Implicit differentiation is a technique used to differentiate equations where the dependent and independent variables are not explicitly separated. Instead of solving for one variable in terms of the other, we differentiate both sides of the equation with respect to the independent variable, applying the chain rule when necessary. This method is particularly useful for equations that define y implicitly in terms of x.
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Chain Rule

The chain rule is a fundamental principle in calculus that allows us to differentiate composite functions. It states that if a function y is defined as a function of u, which in turn is a function of x, then the derivative of y with respect to x can be found by multiplying the derivative of y with respect to u by the derivative of u with respect to x. This is essential in implicit differentiation, where y is often a function of x.
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Exponential Functions

Exponential functions are mathematical functions of the form f(x) = a^x, where a is a constant and x is the variable. In the context of the given problem, the equation x = e^y involves the natural exponential function, where e is the base of natural logarithms. Understanding the properties of exponential functions, including their derivatives, is crucial for applying implicit differentiation effectively.
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Related Practice
Textbook Question

Highway travel A state patrol station is located on a straight north-south freeway. A patrol car leaves the station at 9:00 A.M. heading north with position function s = f(t) that gives its location in miles t hours after 9:00 A.M. (see figure). Assume s is positive when the car is north of the patrol station. <IMAGE>

a. Determine the average velocity of the car during the first 45 minutes of the trip.

Textbook Question

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a. At what rate is the area of the triangle changing when the legs are 5 m long?

Textbook Question

Use definition (2) (p. 135) to find the slope of the line tangent to the graph of f at P.

f(x) = x2 - 4; P(2, 0)

Textbook Question

79–82. {Use of Tech} Visualizing tangent and normal lines <IMAGE>

a. Determine an equation of the tangent line and the normal line at the given point (x0, y0) on the following curves. (See instructions for Exercises 73–78.)

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Textbook Question

The volume V of a sphere of radius r changes over time t.

a. Find an equation relating dV/dt to dr/dt.

Textbook Question

{Use of Tech} Approximating derivatives Assuming the limit exists, the definition of the derivative f′(a) = lim h→0 f(a + h) − f(a) / h implies that if ℎ is small, then an approximation to f′(a) is given by

f' (a) ≈ f(a+h) - f(a) / h. If ℎ > 0 , then this approximation is called a forward difference quotient; if ℎ < 0 , it is a backward difference quotient. As shown in the following exercises, these formulas are used to approximate f′ at a point when f is a complicated function or when f is represented by a set of data points. <IMAGE>

Let f (x) = √x.

a. Find the exact value of f' (4).