Intermediate Algebra (12th Edition)

Published by Pearson
ISBN 10: 0321969359
ISBN 13: 978-0-32196-935-4

Chapter 9 - Chapter 9 Test - Page 640: 2

Answer

$f(^{-1}(x)=x^3-7$

Work Step by Step

Let $y=f(x)$. Then the given one-to-one function, $ f(x)=\sqrt[3]{x+7} ,$ becomes \begin{align*}\require{cancel} y&=\sqrt[3]{x+7} .\end{align*} To find the inverse, interchange the $x$ and $y$ variables and then solve for $y$. That is, \begin{align*} x&=\sqrt[3]{y+7} &(\text{interchange $x$ and $y$}) \\ (x)^3&=\left(\sqrt[3]{y+7}\right)^3 &(\text{solve for $y$}) \\ x^3&=y+7 \\ x^3-7&=y .\end{align*} Hence, the inverse of $ f(x)=\sqrt[3]{x+7} $ is $ f(^{-1}(x)=x^3-7 $.
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