Precalculus: Concepts Through Functions, A Unit Circle Approach to Trigonometry (3rd Edition)

Published by Pearson
ISBN 10: 0-32193-104-1
ISBN 13: 978-0-32193-104-7

Chapter 4 - Exponential and Logarithmic Functions - Chapter Test - Page 372: 3

Answer

$f^{-1}(x)=\frac{5x+2}{3x}$. domain and range of $f(x)$: $\{x|x\ne\frac{5}{3} \}$ and $\{y|y\ne0\}$. domain and range of $f^{-1}(x)$: $\{x|x\ne0 \}$ and $\{y|y\ne\frac{5}{3}\}$.

Work Step by Step

1. $f(x)=\frac{2}{3x-5} \Longrightarrow y=\frac{2}{3x-5} \Longrightarrow x=\frac{2}{3y-5} \Longrightarrow y=\frac{5x+2}{3x} \Longrightarrow f^{-1}(x)=\frac{5x+2}{3x}$. 2. Check $(f\circ f^{-1})(x)=\frac{2}{3(\frac{5x+2}{3x})-5}=x$ and $(f^{-1}\circ f)(x)=\frac{5(\frac{2}{3x-5})+2}{3(\frac{2}{3x-5})}=x$. 3. The domain and range of $f(x)$: $\{x|x\ne\frac{5}{3} \}$ and $\{y|y\ne0\}$. The domain and range of $f^{-1}(x)$: $\{x|x\ne0 \}$ and $\{y|y\ne\frac{5}{3}\}$.
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