Question

((n+1)!)/((n-1)!)=90 nilai n = .....

Answer 1

(n+1)!/(n-1)!=90
(n+1)n(n-1)!/(n-1)!=90
(n+1)n=90
n^2+n-90=0
(n+10)(n-9)=0
n=-10 v n=9

Answer 2

(n+1)!/(n-1)!=90
n.(n+1)=90
n^2 + n - 90 = 0
(n+10)(n-9)=0
n=-10 atau n=9