So it's the square root of x plus delta x minus f of x, in this case, the square root of x. All of that over the change in x, over delta x. So what I'm going to do, right now when I look at that, there's not much simplification I can do to make this come out with something meaningful. I'm going to multiply this fraction times, I'm going to multiply the numerator and the denominator by the conjugate of the numerator. So what do I mean by that? Let me rewrite it. Limit as delta x approaches 0.