Elementary and Intermediate Algebra: Concepts & Applications (6th Edition)

Published by Pearson
ISBN 10: 0-32184-874-8
ISBN 13: 978-0-32184-874-1

Chapter 12 - Exponential Functions and Logarithmic Functions - 12.3 Logarithmic Functions - 12.3 Exercise Set - Page 803: 48

Answer

The graph is shown below.

Work Step by Step

$f\left( x \right)={{4}^{x}}$and ${{f}^{-1}}\left( x \right)={{\log }_{4}}x$ $f\left( x \right)={{4}^{x}}$ Substitute $x=0$ in $f\left( x \right)={{4}^{x}}$: $\begin{align} & f\left( x \right)={{4}^{0}} \\ & =1 \end{align}$ Substitute $x=1$ in $f\left( x \right)={{4}^{x}}$: $\begin{align} & f\left( x \right)={{4}^{1}} \\ & =4 \end{align}$ Substitute $x=2$ in $f\left( x \right)={{4}^{x}}$: $\begin{align} & f\left( x \right)={{4}^{2}} \\ & =16 \end{align}$ Substitute $x=-1$ in $f\left( x \right)={{4}^{x}}$: $\begin{align} & f\left( x \right)={{4}^{-1}} \\ & =\frac{1}{4} \end{align}$ Substitute $x=-2$ in $f\left( x \right)={{4}^{x}}$: $\begin{align} & f\left( x \right)={{4}^{-2}} \\ & =\frac{1}{16} \end{align}$ $\begin{matrix} x & f\left( x \right) \\ 0 & 1 \\ 1 & 4 \\ 2 & 16 \\ -1 & \frac{1}{4} \\ -2 & \frac{1}{16} \\ \end{matrix}$ Consider the second function, ${{f}^{-1}}\left( x \right)={{\log }_{4}}x$ Assume, ${{f}^{-1}}\left( x \right)=y$ The function $y={{\log }_{4}}x$ can be written as ${{4}^{y}}=x$. Substitute $y=0$ in $x={{4}^{y}}$: $\begin{align} & x={{4}^{0}} \\ & =1 \end{align}$ Substitute $y=1$ in $x={{4}^{y}}$: $\begin{align} & x={{4}^{1}} \\ & =2 \end{align}$ Substitute $y=2$ in $x={{4}^{y}}$: $\begin{align} & x={{4}^{2}} \\ & =16 \end{align}$ Substitute $y=-1$ in $x={{4}^{y}}$: $\begin{align} & x={{4}^{-1}} \\ & =\frac{1}{4} \end{align}$ Substitute $y=-2$ in $x={{4}^{y}}$: $\begin{align} & x={{4}^{-2}} \\ & =\frac{1}{16} \end{align}$ $\begin{matrix} x & y \\ 1 & 0 \\ 4 & 1 \\ 16 & 2 \\ \frac{1}{4} & -1 \\ \frac{1}{16} & -2 \\ \end{matrix}$ Now, draw the graph of both functions.
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