\(\dfrac{3\sqrt{x}-x}{3+2\sqrt{x}-x}\) (ĐK: \(x\ne9,x\ge0\))
\(=\dfrac{\sqrt{x}\left(3-\sqrt{x}\right)}{3+3\sqrt{x}-\sqrt{x}-x}\)
\(=\dfrac{\sqrt{x}\left(3-\sqrt{x}\right)}{3\left(1+\sqrt{x}\right)-\sqrt{x}\left(1+\sqrt{x}\right)}\)
\(=\dfrac{\sqrt{x}\left(3-\sqrt{x}\right)}{\left(1+\sqrt{x}\right)\left(3-\sqrt{x}\right)}\)
\(=\dfrac{\sqrt{x}}{\sqrt{x}+1}\)
\(=\dfrac{x-3\sqrt{x}}{x-2\sqrt{x}-3}\)
\(=\dfrac{\sqrt{x}\left(\sqrt{x}-3\right)}{x-3\sqrt{x}+\sqrt{x}-3}\)
\(=\dfrac{\sqrt{x}\left(\sqrt{x}-3\right)}{\left(\sqrt{x}-3\right)\left(\sqrt{x}+1\right)}=\dfrac{\sqrt{x}}{\sqrt{x}+1}\)
