a: \(P=\left(\dfrac{\sqrt{x}}{x+1}+\dfrac{1}{x+1}\right)\cdot\dfrac{x+1}{\sqrt{x}-1}=\dfrac{\sqrt{x}+1}{\sqrt{x}-1}\)
b: Khi \(x=\dfrac{2+\sqrt{3}}{2}=\dfrac{4+2\sqrt{3}}{4}\) thì
\(P=\left(\dfrac{\sqrt{3}+1}{2}+1\right):\left(\dfrac{\sqrt{3}+1}{2}-1\right)\)
\(=\dfrac{\sqrt{3}+3}{2}:\dfrac{\sqrt{3}-1}{2}=\dfrac{3+\sqrt{3}}{\sqrt{3}-1}\)