Well, du is going to be, it's going to be, well, natural log of two is just a constant, so it's going to be three x squared times the natural log of two. And we can actually just change the order we're multiplying a little bit. We could say that this is the same thing as x squared times three natural log of two, which is the same thing, just using logarithm properties, as x squared times the natural log of two to the third power. Three natural log of two is the same thing as the natural log of two to the third power. So this is equal to x squared times the natural log of eight. So let's see, if this is u, where is du? Oh, and of course, we can't forget the dx.