Răspunsuri

2014-05-04T14:40:12+03:00
(n+2)!=n!(n+1)(n+2)
Inlocuim in ecuatie si obtinem:
n!(n+1)(n+2)=20n!
Se simplifica n!:
(n+1)(n+2)=20
n^2+2n+n+2-20=0
n^2+3n-18=0
delta=9+72=81
n1,=3
n2=-6
deci avem 2 solutii n=3,n=-6
1 5 1