I found u=ln x. du/dx = 1/x and du= 1/x dx. I found the new limits, 1 (lower) 2 (upper). So the new equation is the integral from 1 to 2 of 1/u^2 du. How do I derivate that so that I can plug in 1 and 2 to solve? I tried ln u x ln u but I don't think that's correct because I did not get 1/2 like the answer is supposed to be...