\(B=\dfrac{2\sqrt{x}-\sqrt{x}-3}{x+3\sqrt{x}}.\dfrac{x+3\sqrt{x}}{\sqrt{x}-2}\)
\(B=\dfrac{\sqrt{x}-3}{\sqrt{x}-2}\)
a) Ta có: \(B=\left(\dfrac{2}{\sqrt{x}+3}-\dfrac{1}{\sqrt{x}}\right):\dfrac{\sqrt{x}-2}{x+3\sqrt{x}}\)
\(=\dfrac{2\sqrt{x}-\sqrt{x}-3}{\sqrt{x}\left(\sqrt{x}+3\right)}\cdot\dfrac{\sqrt{x}\left(\sqrt{x}+3\right)}{\sqrt{x}-2}\)
\(=\dfrac{\sqrt{x}-3}{\sqrt{x}-2}\)