Intermediate Algebra for College Students (7th Edition)

Published by Pearson
ISBN 10: 0-13417-894-7
ISBN 13: 978-0-13417-894-3

Chapter 8 - Test - Page 659: 16

Answer

Vertex: $(-1,4)$ No $x$-intercept $y$-intercept: $5$

Work Step by Step

The function is in the vertex form $f(x)=a(x-h)^2+k$: $$\begin{align*} f(x)&=(x+1)^2+4. \end{align*}$$ Identify the constants $a$, $h$, $k$: $$\begin{align*} a&=1\\ h&=-1\\ k&=4. \end{align*}$$ Determine the vertex of the function: $$(h,k)=(-1,4).$$ The axis of symmetry is $x=-1$. It opens upward because $a>0$. Determine the $x$-intercepts by solving the equation $f(x)=0$: $$\begin{align*} (x+1)^2+4&=0\\ (x-1)^2&=-4. \end{align*}$$ There is no $x$-intercept. Determine the $y$-intercept: $$f(0)=(0+1)^2+4=5.$$ The $y$-intercept is $5$. We plot the vertex $(-1,4)$, the $y$-intercept point $(0,5)$ and two other points $(-3,8)$ and $(1,8)$, then join them to sketch the graph of the function:
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