Appendix A - Equations and Inequalities - Page 418: 97

$-9$ $\leq$ $x$ $\leq$ $9$ The equivalent interval notation is $[-9, 9]$.

$-4$ $\leq$ $\frac{x + 1}{2}$ $\leq$ $5$ $-4 * 2$ $\leq$ $x + 1$ $\leq$ $5 * 2$ $-8 - 1$ $\leq$ $x$ $\leq$ $10 - 1$ $-9$ $\leq$ $x$ $\leq$ $9$ The equivalent interval notation is $[-9, 9]$.