13C9 - 12C8 = 715 - 495 = ____?
nCr = n!/r!(n-r)!
- 13C9 = 13!/9!(12-9)! = (13*12*11*10)/((4*3*2) = 715
- 12C8 = 12!/8!(12-8)! = (12*11*10*9)/(4*3*2) = 495
Zainab J.
asked 06/26/18
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Zainab J.
06/26/18