And then whatever this expression ends up being algebraically I'm going to evaluate it at x equals two and at x equals one. And so then you use the u substitution right over here and you would get, this would simplify using the same substitution as the integral of u, u to the third power du, u to the third power du. And once again you're going to evaluate this whole thing from x equals two and then subtract from that, it evaluated at x equals one. And so this is going to be equal to, well let's see, this is u to the fourth power over four. And once again evaluating it at x equals two and then subtracting from that at x equals one. And then now we can just back substitute. We could say hey look, u is equal to x squared plus one.