Partial Fractions
The idea and explanations -
http://tutorial.math.lamar.edu/AllBrowsers/2414/PartialFractions.asp
Problems with solutions, see:
http://archives.math.utk.edu/visual.calculus/4/partial_fractions.1/
http://archives.math.utk.edu/visual.calculus/4/partial_fractions.3/