`B=frac{3x-4}{x-2\sqrt{x}}-frac{\sqrt{x}+2}{\sqrt{x}}+frac{\sqrt{x}-1}{2-\sqrt{x}}`
`=frac{3x-4}{\sqrt{x}(\sqrt{x}-2)}-frac{(\sqrt{x}+2)(\sqrt{x}-2)}{\sqrt{x}(\sqrt{x}-2)}-frac{\sqrt{x}(\sqrt{x}-1)}{\sqrt{x}(\sqrt{x}-2)}`
`=frac{3x-4-(x-4)-\sqrt{x}(\sqrt{x}-1)}{\sqrt{x}(\sqrt{x}-2)}`
`=frac{3x-4-x+4-x+\sqrt{x}}{\sqrt{x}(\sqrt{x}-2)}`
`=frac{x+\sqrt{x}}{\sqrt{x}(\sqrt{x}-2)}`
`=frac{\sqrt{x}(\sqrt{x}+1)}{\sqrt{x}(\sqrt{x}-2)}`
`=frac{\sqrt{x}+1}{\sqrt{x}-2}`
nhận thấy `C=frac{\sqrt{x}+1}{\sqrt{x}-2}`
`=>đpcm`
