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[lovehuyen28]

$\left\{\begin{matrix}\sqrt{x+y} + \sqrt{x+3} = \frac{y-3}{x} &  & \\ \sqrt{x+y} +\sqrt{x}=x+3&  &\end{matrix}\right.$

 

Edited by E. Galois, 24-10-2013 - 19:45.

[N H Tu prince]

$\left\{\begin{matrix}\sqrt{x+y} + \sqrt{x+3} = \frac{y-3}{x} &  & \\ \sqrt{x+y} +\sqrt{x}=x+3&  &\end{matrix}\right.$

ĐK:$\left\{\begin{matrix}
 y\ge 3 \\
 x\ge 0
\end{matrix}\right.$

Phương trình (1) tương đương với $\dfrac{y-3}{\sqrt{x+y}-\sqrt{x+3}}=\dfrac{y-3}{x}$

$\Leftrightarrow (y-3)\left(\dfrac{1}{\sqrt{x+y}-\sqrt{x+3}}-\frac{1}{x} \right)=0\Leftrightarrow y=3$