Question

УПРОСТИТЕ ВЫРАЖЕНИЕ
* P - факториал

$frac{P_{(n+2)} }{ P_{n} }$

Answer 1

$P_{n}=n! ; n!=n*(n-1)*(n-2)*(n-3)...$
$frac{P_{n+2}}{P_{n}}=frac{(n+2)!}{n!}=frac{(n+2)(n+1)*n!}{n!}=(n+2)(n+1)=n^{2}+3n+2$