## Precalculus: Mathematics for Calculus, 7th Edition

(-$\infty$,-2] $\cup$ [1,3]
(x+2)(x-1)(x-3) $\leq$ 0 Factors are zero when x=-2, x=1 or x=3, these three points create four intervals, endpoints satisfy the inequality, plug in values from these intervals to decide which of them satisfy the inequality.