Precalculus (6th Edition)

Published by Pearson
ISBN 10: 013421742X
ISBN 13: 978-0-13421-742-0

Chapter 1 - Equations and Inequalities - 1.8 Absolute Value Equations and Inequalities - 1.8 Exercises - Page 169: 88

Answer

$\{-1, \frac{5}{2}, \frac{3\pm i\sqrt {39}}{4} \}$

Work Step by Step

Step 1. Given $|2x^2-3x|=5$, remove the absolute sign to get $2x^2-3x=5$ and $2x^2-3x=-5$ Step 2. For $2x^2-3x=5$, we have $2x^2-3x-5=0$ or $(x+1)(2x-5)=0$ which gives $x=-1, \frac{5}{2}$ Step 3. For $2x^2-3x=-5$, we have $2x^2-3x+5=0$ which gives $x=\frac{3\pm\sqrt {1-4(2)(5)}}{2(2)}=\frac{3\pm i\sqrt {39}}{4}$ Step 4. Combine the above results, the solution set is $\{-1, \frac{5}{2}, \frac{3\pm i\sqrt {39}}{4} \}$
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