Precalculus (10th Edition)

Published by Pearson
ISBN 10: 0-32197-907-9
ISBN 13: 978-0-32197-907-0

Chapter 5 - Exponential and Logarithmic Functions - 5.2 One-to-One Functions; Inverse Functions - 5.2 Assess Your Understanding - Page 267: 72

Answer

(a) $ f^{-1}(x)=\frac{2x-4}{x+3}$. (b) $f$: $(-\infty,2)U(2,\infty)$ and $(-\infty,-3)U(-3,\infty)$. $f^{-1}$: $(-\infty,-3)U(-3,\infty)$ and $(-\infty,2)U(2,\infty)$.

Work Step by Step

(a) $f(x)=\frac{-3x-4}{x-2} \longrightarrow y=\frac{-3x-4}{x-2} \longrightarrow x=\frac{-3y-4}{y-2} \longrightarrow y=\frac{2x-4}{x+3} \longrightarrow f^{-1}(x)=\frac{2x-4}{x+3}$. Check $f(f^{-1})=\frac{-3(\frac{2x-4}{x+3})-4}{\frac{2x-4}{x+3}-2}=x$ and $f^{-1}(f)=\frac{2(\frac{-3x-4}{x-2})-4}{\frac{-3x-4}{x-2}+3}=x$ (b) Domain and range of $f$: $(-\infty,2)U(2,\infty)$ and $(-\infty,-3)U(-3,\infty)$. Domain and range of $f^{-1}$: $(-\infty,-3)U(-3,\infty)$ and $(-\infty,2)U(2,\infty)$.
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