The function is
and the interval is
.
Average rate of change of the function is
.
Find the average rate of change in the interval
.

The average rate of change in the interval
is
.
Find the instantaneous rate of change in the interval
.
Instantaneous rate of change is the derivative of the function.
\
Apply derivative on each side with respect to
.

Instantaneous rate of change at
is
.
Instantaneous rate of change at
is
.
Instantaneous rate of change in the interval
is
.
Hence the average rate of change and the average instantaneous rates are approximately equal.
\The average rate of change in the interval
is
.
Instantaneous rate of change
is
.
Instantaneous rate of change
is
.