If mn+1 pairs of letters are written down,each pair consisting of one chosen from the m letters a1,a2,....and the other from letters b1,b2,.....bn , then show that there are at least two pairs identical.
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2 Answers
Lokesh Verma
·2008-11-01 00:07:31
The maximum number of unique pairs that can be made is m.n.
Hence, the number of pairs will be mn
but since we need mn+1 pairs it has to come from repetition of one of these mn pairs