Prove that if n>=2, then Σ (-1)^(r-1) r n!/(r!n-r!) = 0
I think it should be done by mathematical induction.
From the examples, I'm assuming that mathematical induction should be used. If you are able, please use this method.
A Binomial Coefficients Proof is provided. The solution is detailed and well presented. The response received a rating of "5/5" from the student who originally posted the question.