What is its area going to be? Well, it's going to be f of 2 plus f of 3. f of 2 is this height, f of 3 is this height, so we're taking the average of those two heights, divided by 2, that's the average of those two heights, times the base, times delta x. And then let's do trapezoid 3. I think you're getting the idea here. Trapezoid 3 is going to be f of 3 plus f of 4, divided by 2 times delta x. And then, let's see, I'm running out of colors. This is trapezoid 4 right over here.