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: 9

Answer

$\left\{ \dfrac{1-\sqrt{57}}{8},\dfrac{1+\sqrt{57}}{8} \right\}$

Work Step by Step

The standard form of the given equation, $ 8m^2-2m=7 ,$ is \begin{array}{l}\require{cancel} 8m^2-2m-7=0 .\end{array} Using $\dfrac{-b\pm\sqrt{b^2-4ac}}{2a}$ (or the Quadratic Formula), the solutions of the quadratic equation, $ 8m^2-2m-7=0 ,$ are \begin{array}{l}\require{cancel} \dfrac{-(-2)\pm\sqrt{(-2)^2-4(8)(-7)}}{2(8)} \\\\= \dfrac{2\pm\sqrt{4+224}}{16} \\\\= \dfrac{2\pm\sqrt{228}}{16} \\\\= \dfrac{2\pm\sqrt{4\cdot57}}{16} \\\\= \dfrac{2\pm\sqrt{(2)^2\cdot57}}{16} \\\\= \dfrac{2\pm2\sqrt{57}}{16} \\\\= \dfrac{2(1\pm\sqrt{57})}{16} \\\\= \dfrac{\cancel{2}(1\pm\sqrt{57})}{\cancel{2}\cdot8} \\\\= \dfrac{1\pm\sqrt{57}}{8} .\end{array} Hence, the solutions are $ \left\{ \dfrac{1-\sqrt{57}}{8},\dfrac{1+\sqrt{57}}{8} \right\} .$
Update this answer!

You can help us out by revising, improving and updating this answer.

Update this answer

After you claim an answer you’ll have 24 hours to send in a draft. An editor will review the submission and either publish your submission or provide feedback.