Apply the mean value theorem to the function f(x)= x^2 +2x on the interval [0,2] to determine any valid conclusion the theorem would make.

I know the formula is f(b)-f(a) / b-a = f'(c)

I ended up with (4+2)-(2) / (2-0) = 2

So do I take that 2 and plug it into the derivative of the equation. I did that and got 2(2)+2=6

I am not sure if I did that right, or what it says about the equation?