Verified answer

[tex]\left \{ {{x+3y=0} \atop {x^{2} +y^{2}-2xy }=9} \right. \left \{ {{x=-3y} \atop {(x-y)^{2}=3 }} \right. \left \{ {{x=-3y} \atop( { -3y-y)}^{2} = 9 \right. \left \{ {{x=-3y} \atop ({-4y})^{2}=9 \right. \\\\\left \{ {{x=-3y} \atop {16y^{2}=9 }} \right.[/tex]

[tex]y^{2} =\frac{9}{16} , |y| = \frac{3}{4}; y = \frac{3}{4} =0.75; y=-0.75[/tex]

при у = 0,75, х = 3у = 3 * 0,75 = 2,25

при у = - 0,75, х = 3у = 3 * 0,75 = - 2,25

Ответ: (2,25; 0,75) и (-2,25; 0,75)