$xy+3x-2y=1$
$⇔3x+xy-2y-1=0$
$⇔x(y+3)-2(y+3)+5=0$
$⇔(y+3)(x-2)=-5$
$ta$ $có:$
$-5=(-1)5=5(-1)=(-5).1=1(-5)$
+)$\left \{ {{y+3=-1} \atop {x-2=5}} \right.$ ⇔$\left \{ {{y=-4} \atop {x=7}} \right.$
+)$\left \{ {{y+3=5} \atop {x-2=-1}} \right.$ ⇔$\left \{ {{y=2} \atop {x=1}} \right.$
+)$\left \{ {{y+3=-5} \atop {x-2=1}} \right.$ ⇔$\left \{ {{y=-8} \atop {x=3}} \right.$
+)$\left \{ {{y+3=1} \atop {x-2=-5}} \right.$ ⇔$\left \{ {{y=-2} \atop {x=-3}} \right.$
