## College Algebra 7th Edition

The solution set is $(-\infty,-3]\cup[3,\infty)$
$x^2\ge9\hspace{0.7cm}{\color{blue}{\text{Given equation}}}$ $\Rightarrow x^2-9\ge0$ $\Rightarrow (x-3)(x+3)\ge0\hspace{0.7cm}{\color{blue}{\text{Factor}}}$ The factors of the left-hand side are $x-3$ and $x+3$. These factors are zero when $x=3$ and $x=-3$. These numbers divide the real line into the intervals $(-\infty,-3),(-3,3),(3,\infty)$ From the diagram and hence the inequality involves $\ge$, the endpoints of the intervals satisfy the inequality. The solution set is $(-\infty,-3]\cup[3,\infty)$