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: 4

Answer

$\left\{ -\dfrac{1}{5},3 \right\}$

Work Step by Step

The standard form of the given equation, $ 5x^2-3=14x ,$ is \begin{array}{l}\require{cancel} 5x^2-14x-3=0 .\end{array} Using $\dfrac{-b\pm\sqrt{b^2-4ac}}{2a}$ (or the Quadratic Formula), the solutions of the given quadratic equation, $ 5x^2-14x-3=0 ,$ are \begin{array}{l}\require{cancel} \dfrac{-(-14)\pm\sqrt{(-14)^2-4(5)(-3)}}{2(5)} \\\\= \dfrac{14\pm\sqrt{196+60}}{10} \\\\= \dfrac{14\pm\sqrt{256}}{10} \\\\= \dfrac{14\pm\sqrt{(16)^2}}{10} \\\\= \dfrac{14\pm16}{10} \\\\= \dfrac{14-16}{10} \text{ OR } \dfrac{14+16}{10} \\\\= \dfrac{-2}{10} \text{ OR } \dfrac{30}{10} \\\\= -\dfrac{1}{5} \text{ OR } 3 .\end{array} Hence, the solutions are $ \left\{ -\dfrac{1}{5},3 \right\} .$
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