Question

Помогите выделенной пожалуйста

Answer 1

$\left \{ {{x-y=7} \atop { x^{2} -2y=13}} \right. \\ \\ \left \{ {{y=x-7} \atop { x^{2} -2\cdot(x-7)=13}} \right. \\ \\\left \{ {{y=x-7} \atop { x^{2} -2x+1=0}} \right. \\ \\ \left \{ {{y=1-7} \atop {x=1}} \right. \\ \\ \left \{ {{y=-6} \atop {x=1}} \right.$