So if I just, if I evaluate this at x, this is going to be minus f of x, g of x. All I did so far is I just applied the definition of the derivative. Instead of applying it to f of x, I applied it to f of x times g of x. So you have f of x plus h, g of x plus h, minus f of x, g of x, all of that over h, limit as h approaches zero. Now why did I put this big, awkward space here? Because just the way I've written it right now, it doesn't seem easy to algebraically manipulate. I don't know how to evaluate this limit.