`(\frac{1}{\sqrt{x}-1}-\frac{1}{\sqrt{x}}):(\frac{\sqrt{x}+1}{\sqrt{x}-2}-\frac{\sqrt{x}+2}{\sqrt{x}-1})`
`text{ +) Điều kiện xác định:}` `x\ne1;x>0;x\ne4`
`=(\sqrt{x}-(\sqrt{x}-1))/(\sqrt{x}(\sqrt{x}-1)):((\sqrt{x}-1)(\sqrt{x}+1)-(\sqrt{x}-2)(\sqrt{x}+2))/((\sqrt{x}-2)(\sqrt{x}-1))`
`=(\sqrt{x}-\sqrt{x}+1)/(\sqrt{x}(\sqrt{x}-1)):(x-1-(x-4))/((\sqrt{x}-2)(\sqrt{x}-1))`
`=1/(\sqrt{x}(\sqrt{x}-1)):(x-1-x+4)/((\sqrt{x}-2)(\sqrt{x}-1))`
`=1/(\sqrt{x}(\sqrt{x}-1)).` `\frac{(\sqrt{x}-2)(\sqrt{x}-1)}{3}`
`=\frac{\sqrt{x}-2}{3\sqrt{x}}`
