1.[tex]\left\{\begin{matrix} xy+x+y=3 & & \\ \frac{1}{x^{2}+2x} + \frac{1}{y^{2}+2y} & & \end{matrix}\right.[/tex] 2.[tex]\left\{\begin{matrix} xy(x+y)=2 & & \\ 9xy(3x-y)+6=26x^{3}-2y^{3} & & \end{matrix}\right.[/tex] 3. [tex]\left\{\begin{matrix} 2x+2y+xy=5 & & \\ 27(x+y)+y^{3}+7=26x^{3}+27x^{2}+9x & & \end{matrix}\right.[/tex]
