a) ĐKXĐ: \(\left\{{}\begin{matrix}x>0\\x\ne1\end{matrix}\right.\)
\(P=\left(\frac{\sqrt{x}}{\sqrt{x}+1}-\frac{\sqrt{x}}{\sqrt{x}-1}+\frac{1}{x-1}\right):\frac{x}{1+2\sqrt{x}}\)
\(=\frac{\sqrt{x}\left(\sqrt{x}-1\right)-\sqrt{x}\left(\sqrt{x}+1\right)+1}{x-1}.\frac{1+2\sqrt{x}}{x}\)
\(=\frac{\left(1-2\sqrt{x}\right)\left(1+2\sqrt{x}\right)}{x\left(x-1\right)}=\frac{1-4x}{x\left(x-1\right)}\)