Integration by parts is not only a very useful techinque for integrating, but it is also one of the techinques that appears more in the IB Mathematics exams. The most important step is to choose the part of the integrand that works better for u or f(x), as a right choice will save you a lot of time (and time is everything in the IB!). Whenever you are in doubt, choose u or f(x) to be the following: