1) $\left\{\begin{matrix} x^{2}+1+xy+y^{2}=4y & \\(x^{2}+1)(x+y-2)=y & \end{matrix}\right.$
2) $\left\{\begin{matrix} x+y-\sqrt{xy}=3 & \\\sqrt{x+1}+\sqrt{y+1}=4 & \end{matrix}\right.$
3) $\left\{\begin{matrix} x^{4}+2x^{3}-5x^{2}+y^{2}-6x-11=0 & \\x^{2}+x=3-\frac{6}{\sqrt{y^{2}-7}} & \end{matrix}\right.$
4) $\left\{\begin{matrix} x^{4}+y^{2}+2x^{2}=2y-6 & \\x^{2}y-x^{2}+y=-3 & \end{matrix}\right.$
5) $\left\{\begin{matrix} xy(y+1)+y^{2}+1=4y & \\ xy^{2}(x+2)+\frac{1}{y^{2}}+y^{2}=5 & \end{matrix}\right.$