Giải hệ phương trình :
1, $\left\{\begin{matrix} \sqrt{8y-x} +x=8& & \\ \sqrt{3y-x}+x+y=2& & \end{matrix}\right.$
2, $\left\{\begin{matrix} x^{2}+y^{2}+1=2x+2y & & \\ (2x-y-2)y=1& & \end{matrix}\right.$
3, $\left\{\begin{matrix} \sqrt{x^{2}+x+2}-\sqrt{x+y}=2 & & \\ \sqrt{x+y}=x-y+1& & \end{matrix}\right.$
4, $\left\{\begin{matrix} x+y+\sqrt{x-y}=8 & & \\ y\sqrt{x-y}=2& & \end{matrix}\right.$