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 - Page 123: 23


$x=-1$ or $x=-21$

Work Step by Step

We solve by completing the square: $x^{2}+22x+21=0$ $x^{2}+22x=-21$ $x^{2}+22x+11^{2}=-21+11^{2}=-21+121=100$ $(x+11)^{2}=100$ $x+11=\pm\sqrt{100}=\pm 10$ $x=-11\pm 10$ $x=-11+10=-1$ or $x=-11-10=-21$ So we have: $x=-1$ or $x=-21$
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