x+5/x-1€N <=>x-1|x+5(divide)
x-1|x+5
x-1|x-1
Le scadem:
x-1|x+5-x+1 => x-1|6 <=>x-1€D6 in N =>
x-1€{1,2,3,6} =>
x€{2,3,4,7}