Ответ:

A[1][5] = 5

9P[4]/3P[2] = 36

C[2][15] = 105

Объяснение:

A[1][5] = 5!/(5-1)! = 5!/4! = 5*4!/4! = 5

(9P[4])/(3P[2]) = (3P[4])/P[2] = 3*4!/2! = 3*4*3*2!/2! = 3*3*4 = 36

C[2][15] = 15!/(2!*(15-2)!) = 15!/(2!*13!) = 15*14*13!/(2!*13!) = 15*14/2 = 15*7 = 105