Applying the Chain Rule Use the data in Tables 3.4 and 3.5 of Example 4 to estimate the rate of change in pressure with respect to time experienced by the runner when she is at an altitude of 13,330 ft. Make use of a forward difference quotient when estimating the required derivatives.
Table of contents
- 0. Functions7h 52m
- Introduction to Functions16m
- Piecewise Functions10m
- Properties of Functions9m
- Common Functions1h 8m
- Transformations5m
- Combining Functions27m
- Exponent rules32m
- Exponential Functions28m
- Logarithmic Functions24m
- Properties of Logarithms34m
- Exponential & Logarithmic Equations35m
- Introduction to Trigonometric Functions38m
- Graphs of Trigonometric Functions44m
- Trigonometric Identities47m
- Inverse Trigonometric Functions48m
- 1. Limits and Continuity2h 2m
- 2. Intro to Derivatives1h 33m
- 3. Techniques of Differentiation3h 18m
- 4. Applications of Derivatives2h 38m
- 5. Graphical Applications of Derivatives6h 2m
- 6. Derivatives of Inverse, Exponential, & Logarithmic Functions2h 37m
- 7. Antiderivatives & Indefinite Integrals1h 26m
- 8. Definite Integrals4h 44m
- 9. Graphical Applications of Integrals2h 27m
- 10. Physics Applications of Integrals 3h 16m
- 11. Integrals of Inverse, Exponential, & Logarithmic Functions2h 34m
- 12. Techniques of Integration7h 39m
- 13. Intro to Differential Equations2h 55m
- 14. Sequences & Series5h 36m
- 15. Power Series2h 19m
- 16. Parametric Equations & Polar Coordinates7h 58m
3. Techniques of Differentiation
The Chain Rule
Problem 3.11
Textbook Question
Find the derivatives of the functions in Exercises 1–42.
𝔂 = 2 tan² x - sec² x

1
Step 1: Identify the function components. The function given is 𝔂 = 2 tan² x - sec² x. This consists of two terms: 2 tan² x and -sec² x.
Step 2: Apply the chain rule to differentiate 2 tan² x. The chain rule states that if you have a function g(x) = f(u(x)), then g'(x) = f'(u(x)) * u'(x). Here, let u(x) = tan x, so tan² x = (tan x)². Differentiate using the chain rule: d/dx [2(tan x)²] = 2 * 2(tan x) * sec² x.
Step 3: Differentiate -sec² x. The derivative of sec x is sec x tan x, so the derivative of sec² x is 2 sec x * sec x tan x = 2 sec² x tan x. Therefore, d/dx [-sec² x] = -2 sec² x tan x.
Step 4: Combine the derivatives from steps 2 and 3. The derivative of the entire function 𝔂 = 2 tan² x - sec² x is the sum of the derivatives of its individual terms: 4 tan x sec² x - 2 sec² x tan x.
Step 5: Simplify the expression if possible. Notice that both terms have a common factor of sec² x tan x. Factor this out to simplify the expression: (4 tan x - 2) sec² x tan x.

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Key Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
Derivative
The derivative of a function measures how the function's output value changes as its input value changes. It is a fundamental concept in calculus that represents the slope of the tangent line to the curve of the function at any given point. The derivative can be computed using various rules, such as the power rule, product rule, and chain rule.
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Trigonometric Functions
Trigonometric functions, such as sine, cosine, tangent, secant, and their inverses, are essential in calculus, especially when dealing with derivatives involving angles. Each function has specific derivatives that can be derived from their definitions or unit circle properties. Understanding these functions and their derivatives is crucial for solving problems involving angles and periodic behavior.
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Chain Rule
The chain rule is a formula for computing the derivative of the composition of two or more functions. It states that if a function y is defined as a composition of two functions, say u(x) and v(u), 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 rule is particularly useful when differentiating functions like tan²(x) or sec²(x) in the given problem.
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