a) ta có : \(x-2\sqrt{x}=0\Leftrightarrow\sqrt{x}\left(\sqrt{x}-2\right)=0\Leftrightarrow\left[{}\begin{matrix}\sqrt{x}=0\\\sqrt{x}-2=0\end{matrix}\right.\)
\(\Leftrightarrow\left[{}\begin{matrix}x=0\\x=4\end{matrix}\right.\) vậy \(x=0;x=4\)
b) ta có : \(x-3\sqrt{x}+2=0\Leftrightarrow x-\sqrt{x}-2\sqrt{x}+2=0\)
\(\Leftrightarrow\sqrt{x}\left(\sqrt{x}-1\right)-2\left(\sqrt{x}-1\right)=0\Leftrightarrow\left(\sqrt{x}-1\right)\left(\sqrt{x}-2\right)=0\)
\(\Leftrightarrow\left[{}\begin{matrix}\sqrt{x}-1=0\\\sqrt{x}-2=0\end{matrix}\right.\) \(\Leftrightarrow\left[{}\begin{matrix}x=1\\x=4\end{matrix}\right.\) vậy \(x=1;x=4\)
c) ta có : \(x+\sqrt{x}-12=0\Leftrightarrow x+4\sqrt{x}-3\sqrt{x}-12=0\)
\(\Leftrightarrow\sqrt{x}\left(\sqrt{x}+4\right)-3\left(\sqrt{x}+4\right)=0\Leftrightarrow\left(\sqrt{x}-3\right)\left(\sqrt{x}+4\right)=0\)
\(\Leftrightarrow\left[{}\begin{matrix}\sqrt{x}-3=0\\\sqrt{x}+4=0\left(L\right)\end{matrix}\right.\) \(\Leftrightarrow x=9\) vậy \(x=9\)
