Is this f of x? Well, f of x might involve a constant. So let's put a constant out here, because notice, if you were to take the derivative of this thing here, the derivative of 24x to the negative two over negative two, we already established is 24x to the negative three. But then if you take the derivative of a constant, well, that just disappears, so you don't see it when you look at the derivative. So we have to make sure that there might be a constant. And I have a feeling, based on the information that they've given us, we're going to make use of that constant. So let me rewrite f of x.