I think x= 16 the answer is 16
Pretty sure this one is 52.6, you should download this app called calculator X, it gives you stuff to help answer these questions
Ans: The average rate of change of function =

(in fraction)
Explanation:The average rate of change of function =

Where
b = 8 (x's upper bound)
a = 0 (x's lower bound)

Hence the average rate of change of function =

(in fraction)
I did the box method and my answer was 64x2 x_sqaured minus 16