Precalculus (6th Edition) Blitzer

Published by Pearson
ISBN 10: 0-13446-914-3
ISBN 13: 978-0-13446-914-0

Chapter 2 - Section 2.3 - Polynomial Functions and Their Graphs - Exercise Set - Page 349: 26

Answer

The zeros are $x=-5$ with multiplicity 1 and $x=-2$ with a multiplicity 2. At $x=-5$ the graph will cross the $x\text{-axis}$ and at $x=-2$, the graph will touch the $x\text{-axis}$ and turn around.

Work Step by Step

For zeros: Let $f\left( x \right)=0$. That is, $\begin{align} & 3\left( x+5 \right){{\left( x+2 \right)}^{2}}\,=0 \\ & \left( x+5 \right){{\left( x+2 \right)}^{2}}=0. \end{align}$ Then, for the values of x, we get, $x=-5,-2$ Now, for multiplicity, $x=-5$, with a multiplicity of 1, because of $\left( x+5 \right)$. $x=-2$, with a multiplicity of 2, because of ${{\left( x+2 \right)}^{2}}$. Since the multiplicity of $x=5$ is odd, the graph will cross only the $x\text{-axis}$. And the multiplicity of $x=-4$ is even, so, the graph will touch the $x\text{-axis}$ and turn around.
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