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: 73

Answer

the solution set is\[\left\{ -\frac{2}{3},4 \right\}\].

Work Step by Step

The given equation can be written as\[\frac{3}{4}{{x}^{2}}-\frac{5}{2}x-2=0\]. Take the LCM so that this equation can be rewritten as \[3{{x}^{2}}-10x-8=0\]. Compare the given equation with the equation\[a{{x}^{2}}+bx+c=0\], where\[a=3,\ b=-10,\text{ and }c=-8\] Now, put these values in the formula \[\begin{align} & x=\frac{-\left( -10 \right)\pm \sqrt{{{\left( -10 \right)}^{2}}-4\times \left( 3 \right)\times \left( -8 \right)}}{2\times 3} \\ & =\frac{-\left( -10 \right)\pm \sqrt{100+96}}{6} \\ & =\frac{10\pm \sqrt{196}}{6} \\ & =\frac{10\pm 14}{6} \end{align}\] Further simplifying \[\begin{align} & x=\frac{10\pm 14}{6} \\ & =\frac{24}{6},\frac{-4}{6} \\ & =4,-\frac{2}{3} \end{align}\] Hence, the solution set is\[\left\{ -\frac{2}{3},4 \right\}\].
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