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: 28

Answer

$x=-\frac{5}{8}\pm\frac{3\sqrt{17}}{8}$

Work Step by Step

We complete the square: $4x^{2}+5x-8=0$ $x^{2}+\frac{5}{4}x-2=0$ $x^{2}+\frac{5}{4}x=2$ $x^{2}+\frac{5}{4}x+\frac{25}{64}=2+\frac{25}{64}=\frac{153}{64}$ $(x+\frac{5}{8})^{2}=\frac{153}{64}$ $x+\frac{5}{8}=\pm\sqrt{\frac{153}{64}}=\pm\frac{3\sqrt{17}}{8}$ $x=-\frac{5}{8}\pm\frac{3\sqrt{17}}{8}$
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