So if I make this a 1 1 2, and then I multiply the outside by two, so I divide by two, multiply by two is one way to think about it. This becomes 1 1. And so doing my u substitution, I get 1 1, that's that 1 1 there, times the integral of, well, I have 1 1 2 dx right over here, which is the same thing as du. So I could put the du either in the numerator, I could put it out here. And then I have one over, this is u squared, u squared plus one. Now you might immediately recognize, what's the derivative of arc tan of u? Well, that would be one over u squared plus one.