#### Answer

(a) $(-\infty, -3)$
(b) $(-3, +\infty)$
(c) There is no interval where the function's value is constant.

#### Work Step by Step

(a) The graph of the function is falling (decreasing) from the left up to $x=-3$. Thus, the function is decreasing in the interval $(-\infty, -3)$.
(b) The graph of the function is rising (increasing) from $x=-3$ to the right. Thus, the function is increasing in the interval $(-3, +\infty)$.
(c) There is no part in the graph where the function's value is constant.