Question

\(\sqrt{9x}+\sqrt{25x}-\sqrt{x}=28\)

Answer 1

đk x >= 0 

\(\sqrt{x}\left(1-\sqrt{x}\right)=0\Leftrightarrow\left[{}\begin{matrix}\sqrt{x}=0\\1-\sqrt{x}=0\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}x=0\\x=1\end{matrix}\right.\)(tm) 

Answer 2

đk x >= 0 

\(3\sqrt{x}+5\sqrt{x}-\sqrt{x}=28\Leftrightarrow7\sqrt{x}=28\Leftrightarrow\sqrt{x}=4\Leftrightarrow x=16\left(tm\right)\)