Tính bằng hai cách :

* Hướng dẫn giải

$$\begin{gathered} \left(\frac{1}{3}-\frac{1}{5}\right)\times \frac{1}{2}=\left(\frac{5}{15}-\frac{3}{15}\right)\times \frac{1}{2}=\frac{2}{15}\times \frac{1}{2}=\frac{2}{30}=\frac{1}{15} \\ \left(\frac{1}{3}-\frac{1}{5}\right)\times \frac{1}{2}=\frac{1}{3}\times \frac{1}{2}-\frac{1}{5}\times \frac{1}{2}=\frac{1}{6}-\frac{1}{10}=\frac{10}{60}-\frac{6}{60}=\frac{4}{60}=\frac{1}{15} \end{gathered}$$