a: ĐKXĐ:x>=0; x<>1
b: Sửa đề: \(D=\dfrac{\sqrt{x}}{\sqrt{x}+1}-\dfrac{\sqrt{x}}{\sqrt{x}-1}-\dfrac{2}{\sqrt{x}+1}\)
\(=\dfrac{x-\sqrt{x}-x-\sqrt{x}}{x-1}-\dfrac{2\sqrt{x}-2}{x-1}\)
\(=\dfrac{-2\sqrt{x}-2\sqrt{x}+2}{x-1}=\dfrac{-4\sqrt{x}+2}{x-1}\)
c: Để P=-2 thì \(-2x+2=-4\sqrt{x}+2\)
=>\(2x-4\sqrt{x}=0\)
=>x-2căn x=0
=>x=0 hoặc x=4