Algebra 1: Common Core (15th Edition)

Published by Prentice Hall
ISBN 10: 0133281140
ISBN 13: 978-0-13328-114-9

Chapter 9 - Quadratic Functions and Equations - 9-6 The Quadratic Formula and the Discriminant - Practice and Problem-Solving Exercises - Page 586: 15


$x=12$ $x={-\dfrac{26}{10}}$

Work Step by Step

$x=\dfrac{-b±{\sqrt {b^{2}-4ac}}}{2a}$ and $5x^{2}-47x-156=0$.Therefore, $a=5$,$b=-47$ and $c=-156$ Substitute the values: $x=\dfrac{-(-47)±{\sqrt {-47^{2}-4(5)(-156)}}}{2(5)}$ =$\dfrac{47±{\sqrt {2209+3120}}}{10}$ =$\dfrac{47± {\sqrt {5329}}}{10}$ =$\dfrac{47±73}{10}$ Separate the equation into plus and minus equations: $x=\dfrac{47+73}{10}=12$ $x=\dfrac{47-73}{10}={-\dfrac{26}{10}}$
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