But this is just the area of trapezoids. I'm not actually a big fan when textbooks write this, because when you see this, it's hard to visualize the trapezoids. When you see this, it's much clearer how you might visualize that. But with that out of the way, let's actually evaluate this. Lucky for us, the math is simple. Our delta x is just 1. And then we just have to evaluate all of this business.