Intermediate Algebra (6th Edition)

Published by Pearson
ISBN 10: 0321785045
ISBN 13: 978-0-32178-504-6

Chapter 8 - Section 8.2 - Solving Quadratic Equations by the Quadratic Formula - Exercise Set - Page 492: 21

Answer

$\left\{ 1,\dfrac{5}{2} \right\}$

Work Step by Step

The standard form of the given equation, $ (m+2)(2m-6)=5(m-1)-12 ,$ is \begin{array}{l}\require{cancel} m(2m)+m(-6)+2(2m)+2(-6)=5(m)+5(-1)-12 \\\\ 2m^2-6m+4m-12=5m-5-12 \\\\ 2m^2-2m-12=5m-17 \\\\ 2m^2+(-2m-5m)+(-12+17)=0 \\\\ 2m^2-7m+5=0 .\end{array} Using $\dfrac{-b\pm\sqrt{b^2-4ac}}{2a}$ (or the Quadratic Formula), the solutions of the quadratic equation, $ 2m^2-7m+5=0 ,$ are \begin{array}{l}\require{cancel} \dfrac{-(-7)\pm\sqrt{(-7)^2-4(2)(5)}}{2(2)} \\\\= \dfrac{7\pm\sqrt{49-40}}{4} \\\\= \dfrac{7\pm\sqrt{9}}{4} \\\\= \dfrac{7\pm\sqrt{(3)^2}}{4} \\\\= \dfrac{7\pm3}{4} \\\\= \dfrac{7-3}{4} \text{ OR } \dfrac{7+3}{4} \\\\= \dfrac{4}{4} \text{ OR } \dfrac{10}{4} \\\\= 1 \text{ OR } \dfrac{5}{2} .\end{array} Hence, the solutions are $ \left\{ 1,\dfrac{5}{2} \right\} .$
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