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Ch. 7 - Transcendental Functions
Hass - Thomas' Calculus 15th Edition
Hass15th EditionThomas' CalculusISBN: 9780137616077Non è quello che usi tu?Cambia libro di testo
Capitolo 7, Problema 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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