2x + 7 / x+1 aflați x € N

Răspuns :

2x+7 / x+1 € N => x+1 / 2x+7 => x+1 / 2x+2+5 => x+1 / 2(x+1)+5 => x+1 / 5 => x+1 poate fi 1 sau 5
caz l : x+1=1 => x=0 € N
caz ll : x+1=5 => x=4 € N
Din cazurile l si ll => x € 0; 4