Intermediate Algebra (12th Edition)

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

Chapter 9 - Review Exercises - Page 636: 4

Answer

one-to-one function inverse: $f^{-1}(x)=\dfrac{x^3+4}{6}$

Work Step by Step

Some of the ordered pairs of the given function, $ f(x)=\sqrt[3]{6x-4} $, are $ \left\{(-2,-2.52)(-1,-2.15),(0,-1.59),(1,1.26),(2,2),...\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=&\sqrt[3]{6x-4} \\\Rightarrow& x=\sqrt[3]{6y-4} &(\text{interchange $x$ and $y$}) \\& (x)^3=\left(\sqrt[3]{6y-4}\right)^3 &(\text{solve for $y$}) \\\\& x^3=6y-4 \\& x^3+4=6y \\\\& \dfrac{x^3+4}{6}=\dfrac{\cancel6y}{\cancel6} \\\\& \dfrac{x^3+4}{6}=y .\end{align*} Hence, the inverse is $ f^{-1}(x)=\dfrac{x^3+4}{6} $.
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