P(n,2)=2C(n,4)n=…….plis bantu

Jawab

P(n,2) = 2 . C(n,4)

n !/ (n-2)! = 2 { n !/ (n-4)!.4!}

n! / (n-2)! = 2 ( n !/ (n-4)!. 24)   } kali silang
n! . (n-4) ! 24 = 2 n!. (n-2)!
12 (n-4)! = (n-2)!
12 (n-4) ! = (n-2)(n-3)(n-4)!
12 = (n-2)(n-3)
12  = (4)(3)
n-2 =4
n= 6