Precalculus (10th Edition)

Published by Pearson
ISBN 10: 0-32197-907-9
ISBN 13: 978-0-32197-907-0

Chapter 2 - Functions and Their Graphs - 2.5 Graphing Techniques: Transformations - 2.5 Assess Your Understanding - Page 106: 97

Answer

$x$-intercept: $-4$ $y$-intercepts: $-2$ and $2$ symmetric with the $x$-axis only

Work Step by Step

Step $1$. For $y^2=x+4$, to get the $x$-intercept/s, let $y=0$ then solve for $x$: $$\begin{align*} 0^2&=x+4\\ 0&=x+4\\ -4&=x \end{align*}$$ Thus, the $x$-intercept is $-4$. Step $2$. To get the $y$-intercept, let $x=0$ then solve for $y$. $$\begin{align*} y^2&=0+4\\ y^2&=4\\ y&\pm2 \end{align*}$$ Thus, the $y$-intercepts are $-2$ and $2$. Step $3$. Check for symmetry with respect to the $x$-axis by replacing $(x, y)$ with $(x,-y)$: $$\begin{align*} (-y)^2&=x+4\\ y^2&=x+4 \end{align*}$$ Since the resulting equation is the same as the original, then the graph of the equation is symmetric with respect to the $x$-axis. Check for symmetry with respect to the $y$-axis by replacing $(x, y)$ with $(-x,y)$: $$\begin{align*} y^2&=-x+4\\ \end{align*}$$ Since the resulting equation is not the same as the original, then the graph of the equation is NOT symmetric with respect to the $y$-axis. Check for symmetry with respect to the origin by replacing $(x, y)$ with $(-x,-y)$: $$\begin{align*} (-y)^2&=-x+4\\ y^2&=-x+4 \end{align*}$$ Since the resulting equation is not the same as the original, then the graph of the equation is NOT symmetric with respect to the origin.
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