#### Answer

(a) is increasing on the interval $(-\infty, -1)$;
(b) has no interval where it is decreasing;
(c) constant on the interval $(-1, +\infty)$

#### Work Step by Step

Based on its graph, the given function:
(a) is increasing on the interval $(-\infty, -1)$;
(b) has no interval where it is decreasing;
(c) constant on the interval $(-1, +\infty)$