Thinking Mathematically (6th Edition)

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

Chapter 6 - Algebra: Equations and Inequalities - 6.5 Quadratic Equations - Exercise Set 6.5 - Page 400: 74

Answer

the solution set is\[\left\{ -\frac{3}{2},3 \right\}\].

Work Step by Step

The given equation can be written as\[\frac{{{x}^{2}}}{3}-\frac{x}{2}-\frac{3}{2}=0\]. Take the LCM so that this equation can be rewritten as \[2{{x}^{2}}-3x-9=0\]. Compare the given equation with the equation\[a{{x}^{2}}+bx+c=0\], where\[a=2,\ b=-3,\text{ and }c=-9\]. Now, put these values in the formula \[\begin{align} & x=\frac{-\left( -3 \right)\pm \sqrt{{{\left( -3 \right)}^{2}}-4\times \left( 2 \right)\times \left( -9 \right)}}{2\times 2} \\ & =\frac{3\pm \sqrt{9+72}}{4} \\ & =\frac{3\pm \sqrt{81}}{4} \\ & =\frac{3\pm 9}{4} \end{align}\] Further simplifying \[\begin{align} & x=\frac{3\pm 9}{4} \\ & =\frac{12}{4},\frac{-6}{4} \\ & =3,-\frac{3}{2} \end{align}\] Hence, the solution set is\[\left\{ -\frac{3}{2},3 \right\}\].
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