Precalculus (6th Edition) Blitzer

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

Chapter 5 - Section 5.4 - Product-to-Sum and Sum-to-Product Formulas - Exercise Set - Page 691: 66

Answer

The required solution is $\left\{ -\frac{1}{2},2 \right\}$

Work Step by Step

The expression can be calculated as provided below: $\begin{align} & 2\left( 1-{{u}^{2}} \right)+3u=0 \\ & 2-2{{u}^{2}}+3u=0 \end{align}$ Then, multiply the equation by -1 and rearrange it: $\begin{align} & -2+2{{u}^{2}}-3u=0 \\ & 2{{u}^{2}}-3u-2=0 \end{align}$ And split the middle term as given below: $\begin{align} & 2{{u}^{2}}-3u-2=0 \\ & 2{{u}^{2}}+u-4u-2=0 \\ & u\left( 2u+1 \right)-2\left( 2u+1 \right)=0 \\ & \left( 2u+1 \right)\left( u-2 \right)=0 \end{align}$ Then, find the possible values of $u$: $\begin{align} & 2u+1=0 \\ & 2u=-1 \\ & u=-\frac{1}{2} \end{align}$ And, $\begin{align} & u-2=0 \\ & u=2 \end{align}$ Thus, the possible values are $-\frac{1}{2}$ and $2$.
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