Well, over here we have x is equal to x1. And this point is the point mx1 plus b. You take x1 into this equation of the line, and you're going to get this point right over here. So that's literally going to be equal to mx1 plus b. That's that first error. We can keep doing it with all of the points. This error right over here is going to be y2 minus mx2 plus b, so y2.