How many subsets with three elements of #A={1,2,3,4,5,6}# containing element "1"?

1 Answer
Wataru
Apr 16, 2017

10 subsets

Explanation:

Since we are interested in subsets of the form: #{1,?,?}#, we need to choose 2 more elements from the remaining 5 elements {2,3,4,5,6}. So, we can count the number of combinations:

#C(5,2)=(5!)/((5-2)!2!)=10# susets

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