## Precalculus: Mathematics for Calculus, 7th Edition

(-$\infty$,-3] $\cup$ [3,$\infty$)
$x^{2}$ $\geq$ 9 $x^{2}$-9 $\geq$ 0 (x+3)(x-3) $\geq$ 0 Factors are zero when x=3 or -3, endpoints satisfy the inequality , plug in numbers from intervals to decide which of them satisfy the inequality.