The Position function is and the time interval is
.
The velocity is defined as rate of change of position with respect to time in the interval
is
.
The velocity in the interval :
Average velocity is .
Find instantaneous velocity at .
Instantaneous velocity is the derivative of the position function with respect to .
Consider the Position function is .
Apply derivative on each side with respect to .
Substitute in the above function.
Instantaneous velocity .
Hence the average velocity in the interval is same as instantaneous velocity at
.
Average velocity is .
Instantaneous velocity .
The average velocity in the interval is same as instantaneous velocity at
.