Question

Cum se calculează : n!=30(n-2)!

Answer 1

n!=30(n-2)! => n(n-1)(n-2)!=30(n-2)! => [ se simplifica (n-2)! ] si obtinem: n(n-1)=30
n^2-n-30 = 0 => delta = b^2-4ac = 121 =>
n1=1-rad(121)/2=1-11/2= -10/2= -5 (nu se poate)
n2=1+rad(121)/2=12/2= 6
=> n = 6.