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Ch. 7 - Transcendental Functions
Hass - Thomas' Calculus 15th Edition
Hass15th EditionThomas' CalculusISBN: 9780137616077Not the one you use?Change textbook
Chapter 7, Problem 7.7.17

In Exercises 13–24, find the derivative of y with respect to the appropriate variable.
17. y = ln(sinh z)

Verified step by step guidance
1
Identify the function given: \(y = \ln(\sinh z)\), where \(\sinh z\) is the hyperbolic sine function.
Recall the chain rule for differentiation: if \(y = \ln(u)\), then \(\frac{dy}{dz} = \frac{1}{u} \cdot \frac{du}{dz}\).
Set \(u = \sinh z\). Then find the derivative of \(u\) with respect to \(z\): \(\frac{du}{dz} = \cosh z\), since the derivative of \(\sinh z\) is \(\cosh z\).
Apply the chain rule: \(\frac{dy}{dz} = \frac{1}{\sinh z} \cdot \cosh z\).
Express the derivative as \(\frac{dy}{dz} = \frac{\cosh z}{\sinh z}\), which can also be written as \(\coth z\) if desired.

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Key Concepts

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

Derivative of the Natural Logarithm Function

The derivative of ln(u), where u is a differentiable function of a variable, is given by (1/u) * (du/dx). This rule allows us to differentiate logarithmic functions by first identifying the inner function and then applying the chain rule.
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Derivative of the Natural Logarithmic Function

Hyperbolic Sine Function and Its Derivative

The hyperbolic sine function, sinh(z), is defined as (e^z - e^(-z))/2. Its derivative with respect to z is cosh(z), which is (e^z + e^(-z))/2. Knowing this derivative is essential when differentiating expressions involving sinh.
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Chain Rule in Differentiation

The chain rule is used to differentiate composite functions. It states that the derivative of a composite function f(g(x)) is f'(g(x)) * g'(x). This rule is crucial when differentiating ln(sinh z), as ln and sinh are nested functions.
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Intro to the Chain Rule