rút gọn P=4/căn x-1 +3/căn x-1 -6 căn x+2 (x>0,x khác 1) R=(1/ căn x-1 -căn x/x-1):1/căn x+1 (x>0 x khác 1)

$P=\dfrac{4}{\sqrt{x}-1}+\dfrac{3}{\sqrt{x}-1}-\dfrac{6}{\sqrt{x}+2}$     ĐK: $x>0;x\neq1$

$P=\dfrac{7}{\sqrt{x}-1}-\dfrac{6}{\sqrt{x}+2}$

$P=\dfrac{7(\sqrt{x}+2)-6(\sqrt{x}-1)}{(\sqrt{x}-1)(\sqrt{x}+2)}$

$P=\dfrac{7\sqrt{x}+14-6\sqrt{x}+6}{(\sqrt{x}-1)(\sqrt{x}+2)}$

$P=\dfrac{\sqrt{x}+20}{(\sqrt{x}-1)(\sqrt{x}+2)}$

Vậy $P=\dfrac{\sqrt{x}+20}{(\sqrt{x}-1)(\sqrt{x}+2)}$

$R=(\dfrac{1}{\sqrt{x}-1}-\dfrac{\sqrt{x}}{x-1}):\dfrac{1}{\sqrt{x}+1}$     ĐK: $x>0;x\neq1$

$R=(\dfrac{1}{\sqrt{x}-1}-\dfrac{\sqrt{x}}{(\sqrt{x}-1)(\sqrt{x}+1)}).(\sqrt{x}+1)$

$R=\dfrac{\sqrt{x}+1-\sqrt{x}}{(\sqrt{x}-1)(\sqrt{x}+1)}.(\sqrt{x}+1)$

$R=\dfrac{1}{\sqrt{x}-1}$

Vậy $R=\dfrac{1}{\sqrt{x}-1}$ với $x>0;x\neq1$