This is the natural log of the square root of x. This is v of u of x. So what I want to do is I want to take the derivative of this outside function with respect to this inside function. 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.