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duynhan1
![](https://blog.hocmai.vn/wp-content/uploads/2017/07/hot.gif)
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[tex]\left{\begin{2x^y^2 + x^2 + 2x =2 } \\{2x^2y - x^2y^2 + 2xy =1}(I)[/tex]
[TEX]\left{\begin{2x^y^2 + (x+1)^2 =3 } \\{2xy(x+1) - x^2y^2 =1} [/TEX]
Đăt [TEX]a=x+1; b=xy[/TEX]
[TEX](I) \Leftrightarrow \left{\begin{2b^2 + a^2 =3 } \\{2ab - b^2 =1} [/TEX]
[TEX]\Leftrightarrow \left{\begin{(a+b)^2 =4 } \\{2ab - b^2 =1}[/TEX]
[TEX]Done!![/TEX]
[tex]\left{\begin{x^2(1+y^2) =2 } \\{x^2y^2 + xy = 3x^2-1}(II)[/tex]
[TEX](II) \Leftrightarrow \left{\begin{x^2= 2-x^2y^2} \\{x^2y^2 + xy = 3(2-x^2y^2) -1} [/TEX]
[TEX]\Leftrightarrow \left{\begin{x^2= 2-x^2y^2} \\{4(xy)^2 + xy -5 = 0} [/TEX]
[TEX]Done!![/TEX]