So let me define, I'll do this in a new color. Let me define the squared error against this line as being equal to the sum of these squared errors. So this error right here, or error 1 we could call it, is y1 minus mx1 plus b. And we're going to square it. So this is the error 1 squared. And then we're going to go to error 2 squared. Error 2 squared is y2 minus mx2 plus b.