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: 26

Answer

$\left\{ -3-\sqrt{11},-3+\sqrt{11} \right\}$

Work Step by Step

The standard form of the given equation, $ x(x+6)=2 ,$ is \begin{array}{l}\require{cancel} x^2+6x=2 \\\\ x^2+6x-2=0 .\end{array} Using $\dfrac{-b\pm\sqrt{b^2-4ac}}{2a}$ (or the Quadratic Formula), the solutions of the quadratic equation, $ x^2+6x-2=0 ,$ are \begin{array}{l}\require{cancel} \dfrac{-(6)\pm\sqrt{(6)^2-4(1)(-2)}}{2(1)} \\\\= \dfrac{-6\pm\sqrt{36+8}}{2} \\\\= \dfrac{-6\pm\sqrt{44}}{2} \\\\= \dfrac{-6\pm\sqrt{4\cdot11}}{2} \\\\= \dfrac{-6\pm\sqrt{(2)^2\cdot11}}{2} \\\\= \dfrac{-6\pm2\sqrt{11}}{2} \\\\= \dfrac{2(-3\pm\sqrt{11})}{2} \\\\= \dfrac{\cancel{2}(-3\pm\sqrt{11})}{\cancel{2}} \\\\= -3\pm\sqrt{11} .\end{array} Hence, the solutions are $ \left\{ -3-\sqrt{11},-3+\sqrt{11} \right\} .$
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