Cross sections of the solid perpendicular to the x-axis are rectangles whose height is x. Express the volume of the solid with a definite integral. So pause this video and see if you can have a go at that. All right, now what's interesting about this is they've just given us the equations for the graphs, but we haven't visualized them yet. And we need to visualize them, or at least I like to visualize them, so I can think about this region that they're talking about. So maybe a first thing to do is think about, well, where do these two lines intersect? So when do we have the same y value?