## calculating coefficients of generating functions [closed]

Could somebody explain me the process on how to find the coefficient of x^12 in

    x^2 - 3x
----------------
(1 - x)^4


Thanks

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I believe this is not the kind of question one should ask at MO. Take a look at the faq, you will find links to a place more appropriate for a question like this: mathoverflow.net/faq#whatnot – Harun Šiljak Apr 8 2010 at 15:32
MO isn't intended for questions that might be asked as HW in a high school/basic undergrad class. Good luck with your question elsewhere. – Ben Webster Apr 8 2010 at 15:40
type "series of (x^2 - 3x)/(1 - x)^4" into wolframalpha. – Kevin O'Bryant Apr 8 2010 at 17:34