Răspuns :
xy-3x+y=3 => xy+y-3x-3=0 => y(x+1)-(x+1)=0 => (y-1)(x+1)=0 => y=1 si x=-1
xy-3x+y-3=x(y-3)+(y-3)=(x+1)(y-3)=0 =>pt x=-1, orice y, pt y=3, orice x.