Question

Calcule C9,4.........................................

Answer 1

C9,4 = n!/p!(n-p)! = 9!/4!(9-4)! = 9x8x7x6x5!/4!5! (corta os 5!) = 9x8x7x6/4! = 
9x8x7x6/4x3x2x1 = 98

Answer 2

C n,p
C = n!/p!(n-p)
C = 9.8.7.6.5/4.(9-4)
C = 9.8.7.6.5/4!5!
C = 9.8.7.6/4.3.2.1
C = 3024/24
C = 126