So if we find the m and the b values that satisfy the system of equations, we have minimized the squared error. And we could just solve it in a traditional way, but I want to rewrite this, because I think it's kind of interesting to see what these really represent. So let's add this mean of the x, y's to both sides of this top equation. And then we're going to have, so if we add the mean of the x, y's to both sides of this top equation, what do we get? We get m times the mean of the x squareds, plus b times the mean of the x's, is equal to, these are going to cancel out, is equal to the mean of the x, y's. That's that top equation. This bottom equation right here, let's add the mean of y to both sides of this equation.