Tính bằng cách thuận tiện: a) \(\frac{3}{8} \times \frac{{19}}{{12}} + \frac{3}{8} \times \frac{5}{{12}}\)
Giải thích
a) \(\frac{3}{8} \times \frac{{19}}{{12}} + \frac{3}{8} \times \frac{5}{{12}}\) \(\begin{array}{l} = \frac{3}{8} \times \left( {\frac{{19}}{{12}} + \frac{5}{{12}}} \right)\\ = \frac{3}{8} \times 2\\ = \frac{3}{4}\end{array}\) | b) \(\frac{4}{7} \times \frac{{17}}{{13}} - \frac{4}{7} \times \frac{4}{{13}}\) \(\begin{array}{l} = \frac{4}{7} \times \left( {\frac{{17}}{{13}} - \frac{4}{{13}}} \right)\\ = \frac{4}{7} \times 1\\ = \frac{4}{7}\end{array}\) |