Rút gọn: A=\left (\frac{2a+(ab)^{\frac{1}{2}}}{3a} \right )^{-1}\left ( \frac{a^{\frac{3}{2}}-b^{\frac{3}{2}}}{a-(ab)^{\frac{1}{2}}}-\frac{a-b}{\sqrt{a}+\sqrt{b}} \right )