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Ch. 7 - Transcendental Functions
Hass - Thomas' Calculus 15th Edition
Hass15th EditionThomas' CalculusISBN: 9780137616077당신이 사용하는 게 아니라요?교과서 변경
7장, 문제 7.3.77

In Exercises 59–86, find the derivative of y with respect to the given independent variable.
77. y = log₃(((x + 1)/(x − 1))^(ln 3))

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Recognize that the function is given by \(y = \log_{3} \left( \left( \frac{x+1}{x-1} \right)^{\ln 3} \right)\). The goal is to find \(\frac{dy}{dx}\).
Use the logarithm power rule to simplify the expression inside the logarithm: \(\log_{3} \left( a^{b} \right) = b \cdot \log_{3}(a)\). Applying this, rewrite \(y\) as \(y = (\ln 3) \cdot \log_{3} \left( \frac{x+1}{x-1} \right)\).
Recall the change of base formula for logarithms: \(\log_{a}(b) = \frac{\ln b}{\ln a}\). Use this to rewrite \(\log_{3} \left( \frac{x+1}{x-1} \right)\) as \(\frac{\ln \left( \frac{x+1}{x-1} \right)}{\ln 3}\).
Substitute this back into \(y\) to get \(y = (\ln 3) \cdot \frac{\ln \left( \frac{x+1}{x-1} \right)}{\ln 3}\). Notice that \(\ln 3\) cancels out, simplifying \(y\) to \(y = \ln \left( \frac{x+1}{x-1} \right)\).
Now differentiate \(y = \ln \left( \frac{x+1}{x-1} \right)\) using the chain rule. The derivative of \(\ln u\) with respect to \(x\) is \(\frac{1}{u} \cdot \frac{du}{dx}\). Here, \(u = \frac{x+1}{x-1}\). Find \(\frac{du}{dx}\) using the quotient rule and then write \(\frac{dy}{dx} = \frac{1}{u} \cdot \frac{du}{dx}\).

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주요 개념

질문에 올바르게 답하기 위해 반드시 이해해야 하는 핵심 개념들은 다음과 같습니다.

Logarithmic Functions and Change of Base

Logarithmic functions express the exponent needed to raise a base to a given number. The change of base formula allows rewriting logarithms with any base in terms of natural logs, which simplifies differentiation, especially when the base is not e.
추천 영상:
05:36
Change of Base Property

Chain Rule

The chain rule is a differentiation technique used when a function is composed of other functions. It states that the derivative of a composite function is the derivative of the outer function evaluated at the inner function times the derivative of the inner function.
추천 영상:
05:02
Intro to the Chain Rule

Logarithmic Differentiation

Logarithmic differentiation involves taking the natural log of both sides of an equation to simplify differentiation of complicated expressions, especially those involving powers and products. It transforms exponents into multipliers, making derivatives easier to compute.
추천 영상:
06:30
Logarithmic Differentiation