f(x)=2x^2-8x from x=2 to x=5. Simplify your answer as much.
We need to find [f(b) - f(a)]/(b - a).
Let a = 2
Let b = 5
f(2) = 2(2)^2 - 8(2)
f(2) = 8 - 16
f(2) = -8
We now find f(5).
f(5) = 2(5)^2 - 8(5)
f(5) = 50 - 40
f(5) = 40
[f(5) - f(2)]/(5 - 2)
(40 - (-8))/(3)
(40 + 8)/3
48/3 = 16
The average rate of change is 16.