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: 24

Answer

$\left\{ -1-i,-1+i \right\}$

Work Step by Step

Using $\dfrac{-b\pm\sqrt{b^2-4ac}}{2a}$ (or the Quadratic Formula), the solutions of the given quadratic equation, $ x^2+2x+2=0 ,$ are \begin{array}{l}\require{cancel} \dfrac{-(2)\pm\sqrt{(2)^2-4(1)(2)}}{2(1)} \\\\= \dfrac{-2\pm\sqrt{4-8}}{2} \\\\= \dfrac{-2\pm\sqrt{-4}}{2} \\\\= \dfrac{-2\pm\sqrt{4}\cdot\sqrt{-1}}{2} \\\\= \dfrac{-2\pm\sqrt{(2)^2}\cdot i}{2} \\\\= \dfrac{-2\pm2i}{2} \\\\= \dfrac{2(-1\pm i)}{2} \\\\= \dfrac{\cancel{2}(-1\pm i)}{\cancel{2}} \\\\= -1\pm i .\end{array} Hence, the solutions are $ \left\{ -1-i,-1+i \right\} .$
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