Question

determine all intervals on which the graph of f is decreasing.

Explanation:

Step1: Identify decreasing intervals

A function is decreasing when its graph falls from left to right (as $x$ increases, $y$ decreases).

1. First interval: From $x=-6$ to $x=-2$, the graph decreases.
2. Second interval: From $x=1$ to $x=4$, the graph decreases.
3. Third interval: From $x=7$ to $x=\infty$, the graph decreases.

Answer:

$(-6, -2)$, $(1, 4)$, $(7, \infty)$