Tính 8/9 - 1/72 - 1/56 - 1/42 - ... - 1/6 - 1/2

* Hướng dẫn giải

$$\begin{gathered} \frac{8}{9}-\frac{1}{72}-\frac{1}{56}-\frac{1}{42}-\mathrm{...}-\frac{1}{6}-\frac{1}{2} \\ =\frac{8}{9}+\frac{1}{9}-\frac{1}{8}+\frac{1}{8}-\frac{1}{7}+\mathrm{...}+\frac{1}{3}-\frac{1}{2}+\frac{1}{2}-1 \\ =\frac{8}{9}+\frac{1}{9}-1=0 \end{gathered}$$