1) Ta có: \(x-2\sqrt{x}=0\)
\(\Leftrightarrow\sqrt{x}\left(\sqrt{x}-2\right)=0\)
\(\Leftrightarrow\left[{}\begin{matrix}x=0\\x=4\end{matrix}\right.\)
2) Ta có: \(6+\sqrt{x}-x=0\)
\(\Leftrightarrow x-\sqrt{x}-6=0\)
\(\Leftrightarrow\left(\sqrt{x}-3\right)\left(\sqrt{x}+2\right)=0\)
\(\Leftrightarrow\sqrt{x}-3=0\)
\(\Leftrightarrow x=9\)
3) Ta có: \(x+3\sqrt{x}-4=0\)
\(\Leftrightarrow\left(\sqrt{x}+4\right)\left(\sqrt{x}-1\right)=0\)
\(\Leftrightarrow\sqrt{x}-1=0\)
\(\Leftrightarrow x=1\)