Question

Find the value of ¹⁵C₄

Answer 1

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