a: Sửa đề: \(P=\left(\sqrt{x}-\dfrac{x+2}{\sqrt{x}+1}\right):\left(\dfrac{\sqrt{x}}{\sqrt{x}+1}-\dfrac{\sqrt{x}-4}{1-x}\right)\)
\(P=\dfrac{x+\sqrt{x}-x-2}{\sqrt{x}+1}:\dfrac{\sqrt{x}\left(\sqrt{x}-1\right)+\sqrt{x}-4}{x-1}\)
\(=\dfrac{\sqrt{x}-2}{\sqrt{x}+1}\cdot\dfrac{x-1}{x-\sqrt{x}+\sqrt{x}-4}\)
\(=\dfrac{\sqrt{x}-1}{\sqrt{x}+2}\)
b: Để P<0 thì căn x-1<0
=>0<=x<1