We can factor out here a minus 2b out of all of these terms. So we have minus 2b times y1 plus y2 plus all the way to yn. So this business, so these terms right over here, these terms right over here when you add them up, give you these terms or this term right over there. And let's just keep going. And then in the next video, we're probably going to run out of time in this one. In the next video I'll simplify this more and I'll actually clean up the algebra a good bit. So then the next term, what is this going to be?