## Precalculus (6th Edition) Blitzer

$[-16,2]$
$-3|x+7|\geq-27\qquad$ ... divide with $(-3)$ ... $\times$(negative) $\Rightarrow$ change direction $|x+7|\leq 9$ ... $|u| \leq c$ is equivalent to $-c \leq u \leq c.$ $-9\leq x+7\leq 9 \qquad$ ... add $-7$ ... $-16\leq x\leq 2$ Borders are included, The solution set is $[-16,2].$