## Precalculus (6th Edition)

(a) $(-3, -1)$ (b) $(-1, +\infty)$ (c) $(-\infty, -3)$
(a) The graph is rising from $x=-3$ to the $x=-1$. Thus, the function is increasing in the interval $(-3, -1)$. (b) The graph is falling from $x=-1$ to the right. Thus, the function is decreasing in the interval $(-1, +\infty)$. (c) The graph is constant (horizontal) from $x=-3$ to the left. Thus, the function is constant in the interval $(-\infty, -3)$.