1/n! - 1/(n+1)! упростить

Question

1/n! - 1/(n+1)! упростить

Answer 1

1) (n+1)! / (n-1)! =

n(n+1)(n-1)! = n2+n? n2

2) (n-4!) / (n-2)! =

(n-4)! / (n-2)(n-3)(n-4)! = 1/n2-5n+6