`P=(\frac{x+2\sqrt{x}-7}{x-9}+\frac{\sqrt{x}-1}{3-\sqrt{x}}):(\frac{1}{\sqrt{x}+3}-\frac{1}{\sqrt{x}-1})`
`=(\frac{x+2\sqrt{x}-7-(\sqrt{x}-1)(\sqrt{x}+3)}{(\sqrt{x}+3)(\sqrt{x}-3)}):(\frac{\sqrt{x}-1-\sqrt{x}-3}{(\sqrt{x}+3)(\sqrt{x}-1)})`
`=\frac{x+2\sqrt{x}-7-x-2\sqrt{x}+3}{(\sqrt{x}-3)(\sqrt{x}+3)}.\frac{(\sqrt{x}+3)(\sqrt{x}-1)}{-4}`
`=\frac{-4.(\sqrt{x}+3)(\sqrt{x}-1)}{(\sqrt{x}-3)(\sqrt{x}+3).-4}`
`=\frac{\sqrt{x}-1}{\sqrt{x}-3}`
`d)P<1`
`->\frac{\sqrt{x}-1}{\sqrt{x}-3}<1`
`<=>\frac{\sqrt{x}-1-\sqrt{x}+3}{\sqrt{x}-3}<0`
`<=>\frac{2}{\sqrt{x}-3}<0`
mà `2>0`
`<=>\sqrt{x}-3<0`
`<=>\sqrt{x}<3`
`<=>x<9`
Vậy `x<9` thì `P<1`
