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: 44

Answer

See explanations. $x\ne1/2$, $x\ne-3/2$

Work Step by Step

Step 1. Given $f(x)=\frac{x-5}{2x+3}$ and $g(x)=\frac{3x+5}{1-2x}$, we have $f(g(x))=\frac{(\frac{3x+5}{1-2x})-5}{2(\frac{3x+5}{1-2x})+3}=\frac{3x+5-5+10x}{6x+10+3-6x}=x$ with $x\ne1/2$ Step 2. We have $g(f(x))=\frac{3(\frac{x-5}{2x+3})+5}{1-2(\frac{x-5}{2x+3})}=\frac{3x-15+10x+15}{2x+3-2x+10}=x$ with $x\ne-3/2$ Step 3. Thus $f$ and $g$ are inverse functions. Step 4. For $f(x)$, we have $x\ne-3/2$ and for $g(x)$, we have $x\ne1/2$ which are also part of the composite requirements.
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