Well, if we just apply the definition of a derivative, that means I'm going to take the limit as h approaches zero. In the denominator, I'm going to have an h. In the denominator, I'm going to write a big, it's going to be a big rational expression. In the denominator, I'm going to have an h. And then I'm going to evaluate this thing at x plus h. So that's going to be f of x plus h, g of x plus h. And from that, I'm going to subtract this thing, evaluate it at f of x. Or, sorry, this thing evaluate it at x. So that's going to be f of x times g of x. And I'm going to put a big, awkward space here, and you're going to see why in a second. So if I just, if I evaluate this at x, this is going to be minus f of x, g of x.