a) \(P=\left(1+\dfrac{1}{\sqrt{x}}\right)\left(\dfrac{1}{\sqrt{x}+1}+\dfrac{1}{\sqrt{x}-1}-\dfrac{2}{x-1}\right)\left(đk:x\ge0,x\ne1\right)\)
\(=\dfrac{\sqrt{x}+1}{\sqrt{x}}.\dfrac{\sqrt{x}-1+\sqrt{x}+1-2}{\left(\sqrt{x}-1\right)\left(\sqrt{x}+1\right)}=\dfrac{2\sqrt{x}}{\sqrt{x}\left(\sqrt{x}+1\right)}=\dfrac{2}{\sqrt{x}+1}\)
b) \(P=\dfrac{2}{\sqrt{x}+1}=\dfrac{2}{\sqrt{2}+1}=\dfrac{2\left(\sqrt{2}-1\right)}{2-1}=2\sqrt{2}-2\)
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