B
botvit


1,[TEX]xy+x+y=x^2-2y^2[/TEX]và [TEX]x\sqrt[]{2y}-y\sqrt[]{x-1}=2x-2y[/TEX]
2,x[TEX]^2+y^2+2x=3 2(x^3+y^3)+6x^2=5+3(x^2+y^2)[/TEX]
2,x[TEX]^2+y^2+2x=3 2(x^3+y^3)+6x^2=5+3(x^2+y^2)[/TEX]
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