Question

Rezolvați ecuația Pn supra2 = Pn minus 2

Answer 1

$\frac{P_n}{2} = P_{n-2}$
$\frac{n!}{2}=(n-2)!$
n! = 2(n-2)!
(n-2)!(n-1)n=2(n-2)!
n(n-1)=2 => n = 2