1. Tentukan nilai n dari n! - (n-2)! / (n-1)! = 1 2. Nyatakan dalam notasi faktorial 8×7×6×5 / 1×2×3 Tolong bantuin ya, pake caranya makasih :)

Mapel : Matematika
Tingkat : Olimpiade SMA
Bab : Kombinatorika

Pembahasan :
1||

[n! - (n - 2)!]/(n - 1)! = 1
n!/(n - 1)! - (n - 2)!/(n - 1)! = 1
n(n - 1)!/(n - 1)! - (n - 2)!/(n - 1)(n - 2)! = 1
n - [1/(n - 1)] = 1
(n² - n - 1)/(n - 1) = 1
n² - n - 1 = n - 1
n² - 2n = 0
n(n - 2) = 0
n = 2
n = 0 (Tidak memenuhi)

2||

8×7×6×5 / 1×2×3
= (8 x 7 x 6 x 5 x 4!)/(3 x 2 x 1 x 4!)
= (8!)/(3!4!)

By : GuruMIPA