Question
prove that (n choose k) = (n-1 choose k-1) (n-1 choose k)
a) By using formula of (n choose k)
b) by breaking subsets of size k into two mutually exclusive classes, one class comprising all those subsets which contain a given element and the other all those which dont
a) By using formula of (n choose k)
b) by breaking subsets of size k into two mutually exclusive classes, one class comprising all those subsets which contain a given element and the other all those which dont