\(a.A=\dfrac{x}{\sqrt{x}-1}-\dfrac{2x-\sqrt{x}}{x-\sqrt{x}}=\dfrac{x}{\sqrt{x}-1}-\dfrac{\sqrt{x}\left(2\sqrt{x}-1\right)}{\sqrt{x}\left(\sqrt{x}-1\right)}=\dfrac{x-2\sqrt{x}+1}{\sqrt{x}-1}=\dfrac{\left(\sqrt{x}-1\right)^2}{\sqrt{x}-1}=\sqrt{x-1}\) \(b.x=3+2\sqrt{2}\left(TM\right)\)
Khi đó , ta có : \(A=\sqrt{3+2\sqrt{2}-1}=\sqrt{2+2\sqrt{2}}\)