\(\begin{array}{l}
\frac{{\sqrt x }}{{x + \sqrt x }} = \frac{1}{3}\,\,\,\,\left( {DK:x > 0} \right)\\
\Leftrightarrow 3\sqrt x = x + \sqrt x \\
\Leftrightarrow x - 2\sqrt x = 0\\
\Leftrightarrow \sqrt x \left( {\sqrt x - 2} \right) = 0\\
\Leftrightarrow \left[ \begin{array}{l}
\sqrt x = 0\\
\sqrt x - 2 = 0
\end{array} \right. \Leftrightarrow \left[ \begin{array}{l}
x = 0\,\,\left( {loai} \right)\\
x = 4
\end{array} \right.
\end{array}\)
vậy phương trình có nghiệm x=4
