[TEX] \left \sqrt{7x+y}+\sqrt{2x+y}=5 \\ \sqrt{2x+y}+x-y=2 [/TEX] .
[tex] \left{x^2 - 5xy +6 y^2 =0 \\ 4x^2+2xy +6x-27=0 [/tex] .
[TEX]\left{\frac{x^4-16}{8x}=\frac{y^4-1}{y}\\{x^2-2xy+y^2=8}[/TEX]
PT Vô tỷ
[TEX]\sqrt{x(x-1)}+\sqrt{x(x+2)}=2\sqrt{x^2}[/TEX]
Giải hệ: [TEX]\left\{x^2=y+2\\ y^2=z+2\\ z^2=x+2.[/TEX] .
PT vô tỷ
[TEX]\frac{x^2}{(1+\sqrt{x+1})^2}=x-4[/TEX] .
[tex] \left{ x^3+y^2=2 \\ x^2+y^2-2x-4y=3 [/tex] .
[TEX]\left 2x-2=\sqrt{y-1}+\frac{1}{\sqrt{y-1}} & \text{ } \\2y-2=\sqrt{x-1}+\frac{1}{\sqrt{x-1}}[/TEX] .
[tex] \left{ x + y - \sqrt{xy} = 3 \\ \sqrt{x + 1} + \sqrt{y + 1} = 4 [/tex]
Đề thi ĐH,CĐ khối A năm 2006
[tex] \left{(x+y)({x}^{2}-{y}^{2})= 45\\ (x-y)( {x}^{2}+ {y}^{2})=85 [/tex]
[TEX]A= {(x-3y+1)}^{2}+{(2{x}^{2}+ay+3)}^{2}[/TEX]
Tìm min theo a
[tex] \left {2x^2+xy-y^2-5x+y+2=0\\x^2+y^2+x+y=4 [/tex] .
[tex] \left {1+x^3+y^3=19x^3\\y+xy^2=-6x^2[/tex]
.
[tex] \left{y^3=x^3(9-x^3)\\x^2y+y^2=6x[/tex]
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