College Algebra 7th Edition

Published by Brooks Cole
ISBN 10: 1305115546
ISBN 13: 978-1-30511-554-5

Chapter 1, Equations and Graphs - Section 1.4 - Solving Quadratic Equations - 1.4 Exercises: 8

Answer

$x=-3$ or $x=7$

Work Step by Step

We solve by factoring: $x^{2}-4x=21$ $x^{2}-4x-21=0$ $(x+3)(x-7)=0$ $x+3=0$ or $x-7=0$ So we have: $x=-3$ or $x=7$
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