(n + 1)!/5(n-1)! = n!/3(n-2)!

Faktorial

(n + 1)! / 5(n - 1)! = n! / 3(n - 2)!
(n + 1) n! / 5(n - 1)(n - 2)! = n! / 3(n - 2)!

yg sm letak dan sm besar pd 2 ruas, dicoret

(n + 1) / 5(n - 1) = 1/3
Kalikan silang
3n + 3 = 5n - 5
5n - 3n = 3 + 5
2n = 8
n = 4 ✔