This is going to be equal to pi times the natural log, the natural log of the absolute value of u, so that we can handle even negative values of u, the natural log of the absolute value of u plus c, just in case we had a constant factor out here, plus c. And we're almost done. We just have to unsubstitute for the u. U is equal to natural log of x. So we end up with this kind of neat looking expression. This entire indefinite integral we have simplified, we have evaluated it. And it is now equal to pi times the natural log, the natural log of the absolute value of u, but u is just the natural log of x. The natural log of x, and then we have this plus c right over here. And we could have assumed that from the get-go, this original expression was only defined for positive values of x, because you have to take the natural log here and it wasn't an absolute value.