187/$ \left\{\begin{matrix} \sqrt{x}+\sqrt{1998-y}=\sqrt{1998} & & \\ \sqrt{1998-x}+\sqrt{y}=\sqrt{1998} & & \end{matrix}\right.$
188/ $ \left\{\begin{matrix} x^{2}+xy +y^{2}=7 & & \\ x^{4}+x^{2}y^{2}+y^{4}=21 & & \end{matrix}\right.$
189/$\left\{\begin{matrix} x^{2}+\frac{1}{y^{2}}+\frac{x}{y}=3 & & \\ x+\frac{1}{y}+\frac{x}{y}=3 & & \end{matrix}\right.$
190/ $ \left\{\begin{matrix} 2x^{2}-y^{2}=1 & & \\ xy + x^{2}=2 & & \end{matrix}\right.$
191/ $ \left\{\begin{matrix} x+xy+y=1 & & \\ x+yz+z=3 & & \\ z+zx+x=7 & & \end{matrix}\right.$
192/ $ \left\{\begin{matrix} x+y=3 & & \\ xz+yt=4 & & \\ xz^{2}+yt^{2}=6 & & \\ xz^{3}+yt^{3}=10 & & \end{matrix}\right.$
193/$\left\{\begin{matrix} x^{3}(y^{2}+3y+3)=3y^{2} & & \\ y^{3}(z^{2}+3z+3)=3z^{2} & & \\ z^{3}(x^{2}+3x+3)=3x^{2} \end{matrix}\right.$
194/$\left\{\begin{matrix} x+y=z^{2} & & \\ x=2(y+z) & & \\ xy=2(z+1)\end{matrix}\right.$
195/ $\left\{\begin{matrix} xy=x+3y & & \\ yz=2(2y+z) & & \\ zx=3(3z+2x) \end{matrix}\right.$
196/$\left\{\begin{matrix} (x+y+z)^2=12t & & \\ (y+z+t)^2=12x & & \\ (z+t+x)^3=12y & & \\ (t+x+y)^2=12z & & \end{matrix}\right.$
197/$\left\{\begin{matrix} x^3=2y-x & & \\ y^3=2x-y & & \end{matrix}\right.$
198/ $\left\{\begin{matrix} x-y=(\sqrt{y}-\sqrt{x})(1+xy) & & \\ x^3+y^3=54 & & \end{matrix}\right.$
199/$\left\{\begin{matrix} (x+y)-\sqrt{\frac{x+y}{x-y}}=\frac{12}{x-y} & & \\ xy=15 & & \end{matrix}\right.$
Bài viết đã được chỉnh sửa nội dung bởi Viet Hoang 99: 29-04-2014 - 19:26