Question

n!(n+4)!/(n+3)!(n-1)!

Answer 1

Ответ:

$\frac{n!(n + 4)!}{(n + 3)!(n - 1)!} = \frac{(n - 1)!n(n + 3)!(n + 4)}{(n + 3)!(n - 1)!} = n(n + 4)$