Intermediate Algebra (12th Edition)

Published by Pearson
ISBN 10: 0321969359
ISBN 13: 978-0-32196-935-4

Chapter 8 - Review Exercises - Page 574: 13

Answer

$\left\{\dfrac{2}{3}\pm\dfrac{\sqrt{2}}{3}i\right\}$

Work Step by Step

In the form $ax^2+bx+c=0,$ the given equation, $ 3p^2=2(2p-1) ,$ is equivalent to \begin{align*}\require{cancel} 3p^2&=2(2p)+2(-1) &(\text{use Distributive Property} \\ 3p^2&=4p-2 \\ 3p^2-4p+2&=0 .\end{align*} The equation above has \begin{align*}a= 3 ,b= -4 ,\text{ and }c= 2 .\end{align*} Using $ x=\dfrac{-b\pm\sqrt{b^2-4ac}}{2a} $ or the Quadratic Formula, then \begin{align*} x&=\dfrac{-(-4)\pm\sqrt{(-4)^2-4(3)(2)}}{2(3)} \\\\&= \dfrac{4\pm\sqrt{16-24}}{6} \\\\&= \dfrac{4\pm\sqrt{-8}}{6} .\end{align*} Using concepts of simplifying radicals, the equation above is equivalent to \begin{align*} x&=\dfrac{4\pm\sqrt{8\cdot(-1)}}{6} \\\\&= \dfrac{4\pm\sqrt{8}\cdot\sqrt{-1}}{6} \\\\&= \dfrac{4\pm\sqrt{4\cdot2}\cdot\sqrt{-1}}{6} \\\\&= \dfrac{4\pm\sqrt{4}\cdot\sqrt{2}\cdot\sqrt{-1}}{6} \\\\&= \dfrac{4\pm2\cdot\sqrt{2}\cdot i}{6} &(\text{use }i=\sqrt{-1}) \\\\&= \dfrac{\cancelto24\pm\cancelto12\cdot\sqrt{2}\cdot i}{\cancelto36} \\\\&= \dfrac{2\pm\sqrt{2}\cdot i}{3} \\\\&= \dfrac{2}{3}\pm\dfrac{\sqrt{2}}{3}i .\end{align*} Hence, the solution set of $ 3p^2=2(2p-1) $ is $ \left\{\dfrac{2}{3}\pm\dfrac{\sqrt{2}}{3}i\right\} $.
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