Tính

- Hướng dẫn giải

$$\begin{gathered} A=\frac{-5}{17}.\frac{-9}{23}+\frac{9}{23}.\frac{-22}{17}+11\frac{9}{23} \\ =\frac{5}{17}.\frac{9}{23}+\frac{9}{23}.\frac{-22}{17}+11+\frac{9}{23} \\ =\frac{9}{23}\left(\frac{5}{17}+\frac{-22}{17}+1\right)+11=11 \end{gathered}$$