Rút gọn P? Tính P khi x =

P=$\left(\frac{\sqrt{x-1}}{3+\sqrt{x-1}}+\frac{x+8}{10-x}\right):\left(\frac{3\sqrt{x-1}+1}{x-3\sqrt{x-1}+1}-\frac{1}{\sqrt{x-1}}\right)$$$\begin{gathered} a) Rút gọn P \\ b) Tính P khi x=\sqrt[4]{\frac{3+2\sqrt{2}}{3-2\sqrt{2}}}-\sqrt[4]{\frac{3-2\sqrt{2}}{3-2\sqrt{2}}} \end{gathered}$$