You just need to do some basic counting.
Let S={1,2,3,..........n}.If x denotes the set of all subsets of S containing exactly two elements having 1 as least element,then what is the cardinality of X?
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7 Answers
Arnab Kundu
·2012-05-14 22:40:11
If 1 is the least element and there are only two elements,..... isnt the number (n-1) only comes to any persons mind immediately?