Step-by-step explanation:
the average change rate is simply the change of the functional values in a given interval relative to the change of the input values.
in short
(f ( interval upper limit) - f (interval lower limit) ) /
(interval upper limit) - (interval lower limit)
and you know that f (x) is usually also called y (the functional result variable).
so, the upper limit is 0, the lower limit is -2.
y (or f (x)) is 6 and 10 at these points.
and we get
(6 - 10) / (0 - -2) = -4 / 2 = -2
