\(A=\sqrt{\dfrac{\sqrt{2}+1}{\sqrt{2}-1}}-\sqrt{3-2\sqrt{2}}\)
\(=\sqrt{\dfrac{\left(\sqrt{2}+1\right)^2}{\left(\sqrt{2}-1\right)\left(\sqrt{2}+1\right)}}-\sqrt{\left(\sqrt{2}-1\right)^2}\)
\(=\sqrt{\left(\sqrt{2}+1\right)^2}-\left|\sqrt{2}-1\right|\)
\(=\sqrt{2}+1-\sqrt{2}+1=2\)
\(B=\left(\dfrac{2\sqrt{x}}{\sqrt{x}+3}-\dfrac{\sqrt{x}+1}{3-\sqrt{x}}+\dfrac{3+7\sqrt{x}}{9-x}\right):\dfrac{1}{\sqrt{x}+3}\)
\(=\left(\dfrac{2\sqrt{x}}{\sqrt{x}+3}+\dfrac{\sqrt{x}+1}{\sqrt{x}-3}-\dfrac{7\sqrt{x}+3}{\left(\sqrt{x}-3\right)\left(\sqrt{x}+3\right)}\right)\cdot\dfrac{\sqrt{x}+3}{1}\)
\(=\dfrac{2\sqrt{x}\left(\sqrt{x}-3\right)+\left(\sqrt{x}+1\right)\left(\sqrt{x}+3\right)-7\sqrt{x}-3}{\left(\sqrt{x}-3\right)\left(\sqrt{x}+3\right)}\cdot\left(\sqrt{x}+3\right)\)
\(=\dfrac{2x-6\sqrt{x}+x+4\sqrt{x}+3-7\sqrt{x}-3}{\sqrt{x}-3}\)
\(=\dfrac{3x-9\sqrt{x}}{\sqrt{x}-3}=3\sqrt{x}\)
