1, $\left\{\begin{matrix} \sqrt{7x+y} + \sqrt{2x+y} = 5 & \\ & \\ \sqrt{2x+y} + x-y=2 & \end{matrix}\right.$
2, $\left\{\begin{matrix} \sqrt{x^{2}+6y}=y+3 & \\ & \\ \sqrt{2x+y}+x-y=4& \end{matrix}\right.$
3, $\left\{\begin{matrix} \sqrt{x+y}=9-\left | x+2y \right | & \\ & \\ x(x+4y-2)+y(4y+2)=41& \end{matrix}\right.$