... n(n-1 C r) = (r+1)(n C r+1) I can only get the left side n (n-1)! / r! (n-1-r)! = (r+1)(n C r+1)
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Originally Posted by nafiro ... n(n-1 C r) = (r+1)(n C r+1) I can only get the left side n (n-1)! / r! (n-1-r)! = (r+1)(n C r+1) .