Answer
The function $f$ is decreasing on the following intervals:
$(-10, -8)$;
$(-2, 0)$; and
$(2, 5)$
Work Step by Step
The graph shows that the function $f$ is decreasing in the following intervals:
$(-10, -8)$;
$(-2, 0)$; and
$(2, 5)$
After all, these are the intervals for which the function is going downward from left to right.