Giai hpt:
1: $\left\{\begin{matrix} x^3+3xy^2=-49 & \\ x^2-8xy+y^2=8y-17x & \end{matrix}\right.$
2: $\left\{\begin{matrix} x^2 -2xy+2y+4=0 & \\ x^2-y^2-2x+2y-3=0 & \end{matrix}\right.$
3: $\left\{\begin{matrix} 4(x^2+y^2)+4xy+\frac{3}{(x+y)^2}=7 & \\ 2x+\frac{1}{x+y}=3 & \end{matrix}\right.$