Precalculus (10th Edition)

Published by Pearson
ISBN 10: 0-32197-907-9
ISBN 13: 978-0-32197-907-0

Appendix A - Review - A.6 Solving Equations - A.6 Assess Your Understanding - Page A52: 89

Answer

$\{-\frac{1}{4},\frac{3}{4}\}$

Work Step by Step

Add $\frac{3}{16}$ to both sides. $x^2-\dfrac{1}{2}x-\dfrac{3}{16}+\dfrac{3}{16}=0+\dfrac{3}{16}$ Simplify. $x^2-\dfrac{1}{2}x=\dfrac{3}{16}$ Complete the square by adding $\left(\dfrac{\frac{-1}{2}}{2}\right)^2=\frac{1}{16}$ to both sides. $x^2-\dfrac{1}{2}x+\dfrac{1}{16}=\dfrac{3}{16}+\dfrac{1}{16}$ Simplify. $x^2-\dfrac{1}{2}x+\dfrac{1}{16}=\dfrac{3+1}{16}\\$ $\\x^2-\dfrac{1}{2}x+\dfrac{1}{16}=\dfrac{4}{16}\\$ $\\x^2-\dfrac{1}{2}x+\dfrac{1}{16}=\dfrac{1}{4}$ Factor on the left side. $\left(x-\dfrac{1}{4}\right)^2=\dfrac{1}{4}$ Take the square root of both sides: $x-\dfrac{1}{4}=\pm \sqrt {\dfrac{1}{4}}$ $x-\dfrac{1}{4}=\pm \dfrac{1}{2}$ Split the expression to obtain: $x-\dfrac{1}{4}=\dfrac{1}{2}\quad $ or $\quad x-\dfrac{1}{4}=-\dfrac{1}{2}$ Add $\frac{1}{4}$ to both sides. $x-\dfrac{1}{4}+\dfrac{1}{4}=\dfrac{1}{2}+\dfrac{1}{4}\quad$ or $\quad x-\dfrac{1}{4}+\dfrac{1}{4}=-\dfrac{1}{2}+\dfrac{1}{4}$ Simplify. $x=\dfrac{3}{4}\quad $ or $\quad x=-\dfrac{1}{4}$ Hence, the solution set is $\{-\frac{1}{4},\frac{3}{4}\}$.
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