Intermediate Algebra (12th Edition)

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

Chapter 9 - Section 9.1 - Inverse Functions - 9.1 Exercises - Page 589: 24

Answer

one-to-one function inverse: $f^{-1}(x)=\sqrt[3]{x-5}$

Work Step by Step

Some of the ordered pairs of the given function, $ f(x)=x^3+5 $, are $ \left\{(-2,-3)(-1,4),(0,5),(1,6),(2,13),...\right\} $. Note that every $y$-coordinate from this function is unique. Hence, the given function is a one-to-one function. To find the inverse, let $y=f(x)$. Then, interchange the $x$ and $y$ variables and solve for $y$. That is, \begin{align*}\require{cancel} y&=x^3+5 \\&\Rightarrow x=y^3+5 &(\text{interchange $x$ and $y$}) \\& x-5=y^3 &(\text{solve for $y$}) \\& \sqrt[3]{x-5}=y \\& y=\sqrt[3]{x-5} .\end{align*} Hence, the inverse is $ f^{-1}(x)=\sqrt[3]{x-5} $.
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