Given the function: f(x)=x^3-4x^2+6x-3

a) Find the average rate of change of the function on the interval [2,4]
b)find the instantaneous rate of change of the function at x=3.

when x=2 , y = 1

when x = 4, y = 27
average rate of change between those points
= (27-1)/(4-2) = 13

f'(x) = 3x^2 - 8x + 6
f'(3) = 27 - 24 + 6 = 9