Mohon bantuannya yang saya ceklis

(n+2)!/(n+2-n)!(n)! = 45
(n+2)!/2!(n)!=45
(n+2)(n+1)(n)!/2!(n)!=45
(n+2)(n+1)/2!=45
n^2 + 3n + 1 = 90
n^2 + 3n -89= 0
menggunakan rumus kecap didapatkan
n=

(n+2)Cn = (n+2)! / (n+2 – n ) n!
45 = (n+2)! / (2) n!
45 = n! (n+1) (n+2) / (2) n!
45 × 2 = (n+1) (n+2)
90 = n² + 3n + 2
n² + 3n – 88 = 0
(n + 11) (n – 8) = 0
n= -11 (tdk memenuhi) n = 8 (memenuhi)