Find n, if `(n+1)!=12xx(n-1)`.

Explanation

`(n+1)!=12xx(n-1)!`
or `(n+1)xx n xx (n-1)!=12xx(n-1)!`
or n(b+1)=12
or `n^(2)+n-12=0`
or (n+4)(n-3)=0
or n=3