Решение систем уравнений второй степени

Решите задачу:

$\left \{ {{x^2-y^2-4} \atop {x-y=-4(x+y)}} \right. \; \left \{ {{(x-y)(x+y)=-4} \atop {x-y=-4(x+y)}} \right. \; \left \{ {{-4(x+y)^2=-4} \atop {x-y=-4(x+y)}} \right. \; \left \{ {{(x+y)^2=1} \atop {x-y=-4(x+y)}} \right. \\\\ \left \{ {{x+y=\pm 1} \atop {x-y=-4(x+y)}} \right. \\\\1)\quad \left \{ {{x+y=-1} \atop {x-y=+4}} \right. \; \left \{ {{2x=3} \atop {2y=-5}} \right. \; \left \{ {{x=1,5} \atop {y=-2,5}} \right.$

$2)\quad \left \{ {{x+y=1} \atop {x-y=-4}} \right. \; \left \{ {{2x=-3} \atop {2y=5}} \right. \left \{ {{x=-1,5} \atop {y=2,5}} \right.$

$Otvet:\; \; (1,5\; ;\; -2,5)\; ,\; (-1,5\; ;\; 2,5)\; .$