ĐK:x≥0,x≠1
\(A=\dfrac{x-\sqrt{x}}{\sqrt{x}-1}+\dfrac{x-1}{\sqrt{x}+1}+\sqrt{x}=\dfrac{\sqrt{x}\left(\sqrt{x}-1\right)}{\sqrt{x}-1}+\dfrac{\left(\sqrt{x}-1\right)\left(\sqrt{x}+1\right)}{\sqrt{x}+1}+\sqrt{x}=\sqrt{x}+\sqrt{x}-1+\sqrt{x}=3\sqrt{x}-1\)
Khi x=\(\sqrt{9+4\sqrt{2}}\) thì \(A=3\sqrt{\sqrt{9-4\sqrt{2}}}-1=3\sqrt{\sqrt{\left(2\sqrt{2}-1\right)^2}}-1=3\sqrt{2\sqrt{2}-1}-1\)