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
6. Derivatives of Inverse, Exponential, & Logarithmic Functions
Logarithmic Differentiation
Problem 3.9.53
Textbook Question
49–55. Derivatives of tower functions (or g^h) Find the derivative of each function and evaluate the derivative at the given value of a.
f (x) = (sin x)^In x; a = π/2
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1
Step 1: Recognize that the function f(x) = (\sin x)^{\ln x} is a tower function of the form g(x)^{h(x)}. To differentiate it, use the logarithmic differentiation technique.
Step 2: Take the natural logarithm of both sides: \ln f(x) = \ln((\sin x)^{\ln x}) = \ln x \cdot \ln(\sin x).
Step 3: Differentiate both sides with respect to x. For the left side, use the chain rule: \frac{d}{dx}[\ln f(x)] = \frac{1}{f(x)} \cdot f'(x). For the right side, use the product rule: \frac{d}{dx}[\ln x \cdot \ln(\sin x)] = \ln(\sin x) \cdot \frac{1}{x} + \ln x \cdot \frac{1}{\sin x} \cdot \cos x.
Step 4: Solve for f'(x) by multiplying both sides by f(x): f'(x) = f(x) \cdot \left(\frac{\ln(\sin x)}{x} + \ln x \cdot \cot x\right).
Step 5: Evaluate f'(x) at x = \frac{\pi}{2}. Substitute x = \frac{\pi}{2} into the expression for f'(x) and simplify, noting that \sin(\frac{\pi}{2}) = 1 and \ln(1) = 0.
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