So that is kind of, we're finished the hardcore algebra stage. The next stage we actually want to optimize. We actually want to optimize this. We actually want to optimize, or actually maybe a better way to talk about it, we want to minimize this expression right over here. We want to find the m and the b values that minimize it. And to help visualize it, we're going to start breaking into a little bit of three-dimensional calculus here. But hopefully it won't be too daunting.