\(\text{Condition}:x,y\ge0\)
\(\hept{\begin{cases}x^2+2x=4-\sqrt{y}\left(M_1\right)\\y^2+2y=4-\sqrt{x}\left(M_2\right)\end{cases}}\)
\(\left(M_1\right)-\left(M_2\right)\Leftrightarrow\left(x^2-y^2\right)+2\left(x-y\right)+\left(\sqrt{x}-\sqrt{y}\right)=0\)
\(\Leftrightarrow\left(x+y\right)\left(\sqrt{x}+\sqrt{y}\right)\left(\sqrt{x}-\sqrt{y}\right)+2\left(\sqrt{x}+\sqrt{y}\right)\left(\sqrt{x}-\sqrt{y}\right)+\left(\sqrt{x}-\sqrt{y}\right)=0\)
\(\Leftrightarrow\orbr{\begin{cases}x=y\\\left(x+y\right)\left(\sqrt{x}+\sqrt{y}\right)+2\left(\sqrt{x}+\sqrt{y}\right)+1=0\left(M_3\right)\end{cases}}\)
x=0 khong phai nghiem PT\(\Rightarrow M_3\)(fail)
Thay x=y vao
:D