I dont think anyone in class understands it, we went over it so quick. The only thing I seem to get is that uv - (integral) vdu = (integral) udv. You are supposed to assign u, v, dv and du, but how do you know which is u and which is v? What is the difference between du and dv? Are you integrating the variable in front of du and integrating the unit in front of dv? How do you know which is which? Why does dv sometimes have one of the variables in it and sometimes another? Beyond that there seem to be so many exceptions and substitutions that I can't begin to get a good handle on it. Is there a website that has basic info for lost people like me?