Now what would du be equal to in that scenario? Well du is going to be the derivative of the natural log of x with respect to x, which is just one over x dx. This is an equivalent statement to saying that du dx is equal to one over x. So do we see a one over x dx anywhere in this original expression? Well it's kind of hiding, it's not so obvious, but this x in the denominator is essentially a one over x and then that's being multiplied by a dx. Let me rewrite this original expression to make a little bit more sense. So the first thing I'm going to do is I'm going to take the pi, I should do that in a different color since I've already used, let me take the pi and just stick it out front.