Thinking Mathematically (6th Edition)

Published by Pearson
ISBN 10: 0321867327
ISBN 13: 978-0-32186-732-2

Chapter 6 - Algebra: Equations and Inequalities - Chapter Summary, Review, and Test - Review Exercises - Page 405: 54

Answer

The solution set is\[\left\{ \frac{3\pm 2\sqrt{6}}{3} \right\}\].

Work Step by Step

This equation can be written as\[3{{x}^{2}}-6x-5=0\]. Compare the given equation with the equation\[a{{x}^{2}}+bx+c=0\]. Here,\[a=3,\,\,b=-6,\text{ and }c=-5\] Now put these values in the quadratic formula\[x=\frac{-b\pm \sqrt{{{b}^{2}}-4ac}}{2a}\]. That is, \[\begin{align} & x=\frac{6\pm \sqrt{{{\left( -6 \right)}^{2}}-4\times 3\times \left( -5 \right)}}{2\times 3} \\ & =\frac{6\pm \sqrt{36+60}}{6} \\ & =\frac{6\pm \sqrt{96}}{6} \\ & =\frac{6\pm 4\sqrt{6}}{6} \end{align}\] Simplify further, \[\begin{align} & x=\frac{6\pm 4\sqrt{6}}{6} \\ & =2\left( \frac{3\pm 2\sqrt{6}}{6} \right) \\ & =\frac{3\pm 2\sqrt{6}}{3} \end{align}\]
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