So, the derivative of natural log of something with respect to that something is one over that something. So it is one over that something. The derivative of natural log of something with respect to that something is one over that something. So that's what we just did here. One way to think about it, what would natural log of x be? Well that'd be one over x, but it's not natural log of x, it's one over square root of x. So, it's going to be one over the square root of x.