It has a coordinate x1, y1. You have the second point over here that has a coordinate x2, y2. And then we keep putting points up here and eventually we get to the nth point over here. So we have the nth point that has the coordinates xn, yn. What we saw is that there is a line that we can find. We can find a line that minimizes the squared distance. So this line right here, I'll call it y is equal to mx plus b.