Chapter 4 Quadratic Functions and Factoring - 4.9 Graph and Solve Quadratic Inequalities - 4.9 Exercises - Skill Practice - Page 304: 29

$x \leq-2$ or $x \geq 4$

Given $x^2 -2x \geq 8$. Rewrite as: $x^2-2x -8 \geq 0$. Then make a table of values: Notice that $x^2 -2x \geq 8$ when $x \leq-2$ or $x \geq 4$. The solution of the inequality is $x \leq-2$ or $x \geq 4$.