Intermediate Algebra for College Students (7th Edition)

Published by Pearson
ISBN 10: 0-13417-894-7
ISBN 13: 978-0-13417-894-3

Chapter 8 - Section 8.1 - The Square Root Property and Completing the Square - Concept and Vocabulary Check - Page 592: 9

Answer

Add $\frac{1}{9}$ to both sides of the equation to complete the square

Work Step by Step

$x^2 -\frac{2}{3}x = \frac{4}{9}$ The coefficient of the x-term is $-\frac{2}{3}$. Half of $-\frac{2}{3}$ is $-\frac{1}{3}$, and $(-\frac{1}{3})^2 = \frac{1}{9}$. Thus, add $\frac{1}{9}$ to both sides of the equation to complete the square. $x^2 -\frac{2}{3}x +\frac{1}{9} = \frac{4}{9} +\frac{1}{9}$ $x^2 -\frac{2}{3}x +\frac{1}{9} = \frac{5}{9}$ $(x-\frac{1}{3})^2 = \frac{5}{9}$ $ x+\frac{1}{3} =\sqrt\frac{5}{9}$ or $ x+\frac{1}{3} =-\sqrt\frac{5}{9}$ $x = -\frac{1}{3}+\sqrt\frac{5}{9}$ or $x = -\frac{1}{3}-\sqrt\frac{5}{9}$ The solutions are $-\frac{1}{3}±\sqrt\frac{5}{9}$.
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