Now what does that mean visually? So let's calculate the average change. The average change between point a and point b, well that's going to be the slope of the secant line. That's going to be the slope of the secant line. So this is the secant line, so think about its slope. All the mean value theorem tells us is that at some point in this interval, the slope of the tangent line is going to be the same as the slope of the secant line. And we can see just visually, it looks like right over here the slope of the tangent line looks like the same as the slope of the secant line.