#Câu_Hệ
\[\left\{\begin{matrix}
\[\left\{\begin{matrix}
x^2+1=-y(y-x+4) & & \\
y(7-x^2-y^2+2xy)=2(x^2+1)& &
\end{matrix}\right.\]
\[\left\{\begin{matrix}
x^2+1=-y(y-x+4) & & \\
y(7-x^2-y^2+2xy)=2-y(y-x+4)& & (II)
\end{matrix}\right.\]
$(II) <=> y=0$
$<=>(7-x^2-y^2+2xy)=2-(y-x+4) <=> (x-y-3)(x-y+5)=0$....đến đây thì dễ rùi