Решите систему уравнений x^2-6xy+9y^2=x-y x-3y=-1

$\left \{ {{x^2-6xy+9y^2=x-y} \atop {x-3y=-1}} \right. \\ \left \{ {{x^2-2*x*3y+(3y)^2=x-y} \atop {x-3y=-1}} \right. \\ \left \{ {{(x-3y)^2=x-y} \atop {x-3y=-1}} \right. \\ -\left \{ {{x-y=1} \atop {x-3y=-1}} \right. \\ \left \{ {{-y+3y=1+1} \atop {x-y=1}} \right. \\ \left \{ {{2y=2} \atop {x=y+1}} \right. \\ \left \{ {{y=1} \atop {x=2}} \right. \\ \left \{ {{x=2} \atop {y=1}} \right.$
Ответ: $(2;1)$