Natural log of the square root of x, which is equal to f of x. So you could view f of x as this entire, as this entire set, or this entire, I guess you could say, this combination of functions right over there. And that is f of x, which is essentially a composition of two functions. You're inputting into one function, then taking that output and inputting it into another. So you could have a function u here, which takes the square root of whatever it's input in, is. So u of x is equal to the square root of x. And then you take another, and then you take that output and input it into another function that we could call v. And what does v do?