Question 459217
Find the average rate of change of f(x) 3x^2-4x from x=3 to x=6 . 

Simplify your answer as much as possible. 
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f(x) = 3x^2 - 4x
The average rate of change is the change in f(x) divided by the change in x.  
So we can write
rate of change = r = (f(6) - f(3))/(6 - 3)
f(6) = 3(6)^2 - 4(6) = 84
f(3) = 3(3)^2 - 4(3) = 15
So r = (84-15)/(6-3) = 23