Question

Помогите, пожалуйста, решить систему

Answer 1

$left { {{(x+2y)^2-2(x-2y)=11} atop {5(x+2y)+x-2y=-18}} right. \\x+2y=u; ,; x-2y=v\\ left { {{u^2-2v=11} atop {5u+v=-18}} right. ; left { {{u^2-2(-5u-18)-11=0} atop {v=-5u-18}} right. ; left { {{u^2+10u+25=0} atop {v=-5u-18}} right. ; left { {{(u+5)^2=0} atop {v=-5u-18}} right. \\ left { {{u=-5} atop {v=25-18=7}} right. ; left { {{x+2y=-5} atop {x-2y=7}} right. ; left { {{x+2y=-5} atop {4y=-12}} right. ; left { {{x=-5-2y} atop {y=-3}} right.$

$left { {{x=-5+6=1} atop {y=-3}} right. \\Otvet:; (1,-3).$