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 - Chapter Review - Page 605: 42


$x=0.15$ or $x=7.85$

Work Step by Step

$-x^2+8x+4=5$ $-x^2+8x-1=0$ Use the quadratic formula. $x=\frac{-(8) \pm \sqrt (8)^2-4.(-1).(-1)}{2.(-1)}$ $x=\frac{-8 \pm 2\sqrt 15}{-2}$ $x=\frac{-8 \pm 7.7}{-2}$ $x=\frac{-8+7.7}{-2}$ or $x=\frac{-8- 7.7}{-2}$ $x=0.15$ or $x=7.85$
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