I'm giving up that area there. But this is just an approximation. And maybe if I had many more rectangles, it would be a better approximation. So let's figure out what the areas of each of the rectangles are. So the area of this first rectangle is going to be the height, which is f of 1 times the base, which is delta x. The area of the second rectangle is going to be the height, which we already said is f of 1.5 times the base times delta x. The height of the third rectangle is going to be the function evaluated at its left boundary, so f of 2, so plus f of 2 times the base times delta x.