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 495: 98

Answer

$\left\{ \dfrac{-\sqrt{7}-3\sqrt{7}}{2},\dfrac{-\sqrt{7}+3\sqrt{7}}{2} \right\}$

Work Step by Step

Using $\dfrac{-b\pm\sqrt{b^2-4ac}}{2a}$ (or the Quadratic Formula), the solutions of the given quadratic equation, $ 7x^2+\sqrt{7}x-2=0 ,$ are \begin{array}{l}\require{cancel} \dfrac{-(\sqrt{7})\pm\sqrt{(\sqrt{7})^2-4(7)(-2)}}{2(1)} \\\\= \dfrac{-\sqrt{7}\pm\sqrt{7+56}}{2} \\\\= \dfrac{-\sqrt{7}\pm\sqrt{9\cdot7}}{2} \\\\= \dfrac{-\sqrt{7}\pm\sqrt{(3)^2\cdot7}}{2} \\\\= \dfrac{-\sqrt{7}\pm3\sqrt{7}}{2} .\end{array} Hence, the solutions are $ \left\{ \dfrac{-\sqrt{7}-3\sqrt{7}}{2},\dfrac{-\sqrt{7}+3\sqrt{7}}{2} \right\} .$
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