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Ch. 7 - Transcendental Functions
Hass - Thomas' Calculus 15th Edition
Hass15th EditionThomas' CalculusISBN: 9780137616077당신이 사용하는 게 아니라요?교과서 변경
7장, 문제 7.3.21

In Exercises 7–26, find the derivative of y with respect to x, t, or θ, as appropriate.
y = ln(e^(θ)/(1+e^θ))

검증된 단계별 안내
1
Rewrite the given function to simplify the expression inside the logarithm: \(y = \ln\left( \frac{e^{\theta}}{1 + e^{\theta}} \right)\).
Use the logarithm property \(\ln\left( \frac{a}{b} \right) = \ln(a) - \ln(b)\) to separate the function into \(y = \ln(e^{\theta}) - \ln(1 + e^{\theta})\).
Simplify \(\ln(e^{\theta})\) using the property \(\ln(e^{x}) = x\), so the function becomes \(y = \theta - \ln(1 + e^{\theta})\).
Differentiate each term with respect to \(\theta\): the derivative of \(\theta\) is 1, and for \(-\ln(1 + e^{\theta})\), apply the chain rule.
For the second term, use the chain rule: \(\frac{d}{d\theta} \left[ -\ln(1 + e^{\theta}) \right] = - \frac{1}{1 + e^{\theta}} \cdot \frac{d}{d\theta} (1 + e^{\theta}) = - \frac{e^{\theta}}{1 + e^{\theta}}\).

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이 영상 해법은 위 문제에 도움이 된다고 튜터들이 추천한 것입니다.
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주요 개념

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

Derivative of the Natural Logarithm Function

The derivative of ln(u), where u is a differentiable function of a variable, is (1/u) times the derivative of u. This rule allows us to differentiate logarithmic expressions by first identifying the inner function and then applying the chain rule.
추천 영상:
05:18
Derivative of the Natural Logarithmic Function

Chain Rule

The chain rule is used to differentiate composite functions. It states that the derivative of a function composed of another 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

Simplification of Exponential Expressions

Simplifying expressions involving exponentials, such as e^θ/(1 + e^θ), helps in easier differentiation. Recognizing that e^θ/(1 + e^θ) can be rewritten or simplified aids in applying derivative rules more efficiently.
추천 영상:
6:39
Simplifying Exponential Expressions