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Question
Find the value of 15C4
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Solution
15C4
= `(15!)/(4!(15 - 4)!) ...(∵ ""^"n""C"_"r" = ("n"!)/("r"!("n" - "r")!))`
= `(15!)/(4!11!)`
= `(15 xx 14 xx 13 xx 12 xx 11!)/(4 xx 3 xx 2 xx 1 xx 11!)`
= `(15xx14xx13xx12)/(4xx3xx2xx1)`
= 1365
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