So the mean value theorem, just as a little bit of a review, as a little bit of review, it says that if we have some type of an interval, if you have an interval, so let me draw some axes right over here. If you have an interval, so let me draw an interval like this. And over that interval, you have a differentiable function. You have a differentiable function. So maybe my function looks like this. It says there's at least one point c on that interval where the derivative at that point c is equal to the average rate of change. So the way I've drawn it right over here, the average rate of change of this function, I'll do it in magenta, is this right over here.