And then we're taking the slope between that point and an arbitrary x value, or I should say an arbitrary other point on the curve. So this right over here would be the point. We could call that x comma x to the third. We know that f of x is equal to x to the third. And let me make it clear. This is a graph of y is equal to x to the third. And so this expression right over here, all of this, this is the slope between these two points.