Câu 28* $\left\{\begin{matrix} (x-1)(y^2+6)=y(x^2+1)\\(y-1)(x^2+6)=x(y^2+1) \end{matrix}\right.$
Câu 29 $\left\{\begin{matrix} \sqrt[3]{(x-1)(y+1)}+x=\sqrt{x^3-2}\\\frac{2(x^3+y^3)}{xy}-\frac{3(x^2+y^2)}{\sqrt{xy}}+5(x+y)=8\sqrt{xy} \end{matrix}\right.$