And what we want to do is remind ourselves, how do we find the slope of that line? And what we do is we take two points on the line. So let's say we take this point right here. Let's say that that is the point x is equal to a. And then what would this be? This would be the point f of a, where the function is going to be some line. We could write f of x is going to be equal to mx plus b.