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: 28

Answer

The zeros are $x=-\frac{1}{2}$ with a multiplicity of 1 and $x=4$ with a multiplicity of 3. At $x=-\frac{1}{2}$ and $x=4$, the graph will cross the $x\text{-axis}$.

Work Step by Step

For zeros, let $f\left( x \right)=0$. That is, $\begin{align} & -3\left( x+\frac{1}{2} \right){{\left( x-4 \right)}^{3}}=0 \\ & \left( x+\frac{1}{2} \right){{\left( x-4 \right)}^{3}}=0. \end{align}$ Then, the values of x are as follows: $x=-\frac{1}{2},4$. For multiplicity: $x=-\frac{1}{2}$, with a multiplicity of 1, because of $\left( x+\frac{1}{2} \right)$. $x=4$, with a multiplicity of 3, because of ${{\left( x-4 \right)}^{3}}$. The multiplicity of $x=-\frac{1}{2}$ is odd; the graph will cross only the $x\text{-axis}$. The multiplicity of $x=4$ is odd; the graph will cross only the $x\text{-axis}$.
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