Question 747168
the key is to rewrite the factorials so that they are in terms of (n-1)!


{{{(n + 1)! + n! + (n - 1)!=(n + 1)*n*(n - 1)!+ n*(n - 1)! + (n-1)!

}}}


{{{
((n + 1)*n+ n + 1)(n-1)!

}}}

and then...


{{{
(n + 1)^2(n-1)!
}}}