SOLUTION: prove that: nCr=nC(n-r)

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Question 21400: prove that: nCr=nC(n-r)
Answer by venugopalramana(3286) About Me  (Show Source):
You can put this solution on YOUR website!
LHS=nCr=n!/[(n-r)!r!]
RHS=nCn-r=n!/[{n-(n-r)}!(n-r)!]=n!/[(n-n+r)!(n-r)!]=n!/[r!(n-r)!]=n!/[(n-r)!r!]=LHS