Question

a). jika nP4 = 42 x nP2.. tentukan nP5

Answer 1

N P4 = 42 x n P2
n ! / (n-4)! = 42 X n!/ (n-2)!
(n-2)! / (n-4)! = 42 .n!/n!
(n-2)(n-3) = 42 = 7(6)
n-2 = 7 --> n = 9
.
nilai  9P5 = 15.120