And as we go, as x's get larger and larger, the disks have a larger and larger radius. So we're going to sum up all of those disks, and we're going to take the limit as each of those disks get infinitely thin, and we have an infinite number of them. But we have to figure out our boundaries of integration. So what are our boundaries of integration? What are the two points right over here where they intersect? Well, we could just set these two things to be equal to each other. If you just said x is equal to square root of x, when does x equal square root of x?