College Algebra 7th Edition

Published by Brooks Cole
ISBN 10: 1305115546
ISBN 13: 978-1-30511-554-5

Chapter 1, Equations and Graphs - Section 1.7 - Solving Inequalities - 1.7 Exercises - Page 148: 42

Answer

The solution set is $(-\infty,-2]\cup[\frac{1}{2},\infty)$

Work Step by Step

$5x^2+3x\ge3x^2+2\hspace{0.7cm}{\color{blue}{\text{Given equation}}}$ $\Rightarrow 5x^2+3x-3x^2-2\ge0$ $\Rightarrow 2x^2+3x-2\ge0$ $\Rightarrow (2x-1)(x+2)\ge0\hspace{0.7cm}{\color{blue}{\text{Factor}}}$ The factors of the left-hand side are $2x-1$ and $x+2$. These factors are zero when $x=\frac{1}{2}$ and $x=-2$. These numbers divide the real line into the intervals $(-\infty,-2),(-2,\frac{1}{2}),(\frac{1}{2},\infty)$ From the diagram and hence the inequality involves $\ge$, the endpoints of the intervals satisfy the inequality. The solution set is $(-\infty,-2]\cup[\frac{1}{2},\infty)$
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