Cho P=(1/√x-1+1/x-1):(2-√x-4/√x-1) a, tìm đkxđ. b, rút gọn P. c, tìm x để P=1/4

`P=(1/(\sqrt{x}-1)+1/(x-1)):(2-(\sqrt{x}4)/(\sqrt{x}-1))`

ĐKXD: `x≥0,x\ne1;4`

`P=(1/(\sqrt{x}-1)+1/(x-1)):(2-(\sqrt{x}-4)/(\sqrt{x}-1))`

`=(\sqrt{x}+1+1)/(x-1):(2\sqrt{x}-2-\sqrt{x}+4)/(\sqrt{x}-1)`

`=(\sqrt{x}+2)/(x-1):(\sqrt{x}+2)/(\sqrt{x}-1)`

`=(\sqrt{x}+2)/((\sqrt{x}-1)(\sqrt{x}+1)) . (\sqrt{x}-1)/(\sqrt{x}+2)`

`=1/(\sqrt{x}+1)`

`P=1/4`

`⇔1/(\sqrt{x}+1)=1/4`

`⇔\sqrt{x}+1=4`

`⇔\sqrt{x}=3`

`⇔x=9(TM)`