Respostas

2014-04-10T12:44:05-03:00

 \frac{(n+1).n.(n-1)!}{(n-1)!} =6

n²+n=6

n²+n-6=0

Δ=1+24=25

n=(-1+5)/2=2

n=(-1-5)/2=-3

1 3 1