Well, to keep going, let's just keep exploring this expression. So all of this is going to be equal to, it's all going to be equal to the limit as h approaches zero. So the first thing I'm going to do is I'm going to look at this part, this part of the expression. And in particular, let's see, I am going to factor out an f of x plus h. So if you factor out an f of x plus h, this part right over here is going to be f of x plus h, f of x plus h, times, you're going to be left with g of x plus h, g of, it's a slightly shader, different shade of green, g of x plus h, that's that there, minus g of x, minus g of x, whoops, I forgot the parentheses. Oh, it's a different color. I got a new software program and it's making it hard for me to change colors. My apologies, this is not a straightforward proof and the least I could do is change colors more smoothly.