2. Приведите дроби к общему знаменателю: а) и 3. 10' 5 7 4 5 7 в) и 12' 15' 21 35

Ответ: a) \(\frac{4}{10}\) и \(\frac{3}{10}\); б) \(\frac{3}{18}\) и \(\frac{10}{18}\); в) \(\frac{9}{24}\) и \(\frac{14}{24}\); г) \(\frac{28}{105}\), \(\frac{25}{105}\) и \(\frac{21}{105}\)

1. а) \(\frac{2}{5}\) и \(\frac{3}{10}\). Общий знаменатель: 10. \(\frac{2}{5} = \frac{2 \cdot 2}{5 \cdot 2} = \frac{4}{10}\). Получаем дроби \(\frac{4}{10}\) и \(\frac{3}{10}\).
2. б) \(\frac{1}{6}\) и \(\frac{5}{9}\). Общий знаменатель: 18. \(\frac{1}{6} = \frac{1 \cdot 3}{6 \cdot 3} = \frac{3}{18}\), \(\frac{5}{9} = \frac{5 \cdot 2}{9 \cdot 2} = \frac{10}{18}\). Получаем дроби \(\frac{3}{18}\) и \(\frac{10}{18}\).
3. в) \(\frac{3}{8}\) и \(\frac{7}{12}\). Общий знаменатель: 24. \(\frac{3}{8} = \frac{3 \cdot 3}{8 \cdot 3} = \frac{9}{24}\), \(\frac{7}{12} = \frac{7 \cdot 2}{12 \cdot 2} = \frac{14}{24}\). Получаем дроби \(\frac{9}{24}\) и \(\frac{14}{24}\).
4. г) \(\frac{4}{15}\), \(\frac{5}{21}\) и \(\frac{7}{35}\). Общий знаменатель: 105. \(\frac{4}{15} = \frac{4 \cdot 7}{15 \cdot 7} = \frac{28}{105}\), \(\frac{5}{21} = \frac{5 \cdot 5}{21 \cdot 5} = \frac{25}{105}\), \(\frac{7}{35} = \frac{7 \cdot 3}{35 \cdot 3} = \frac{21}{105}\). Получаем дроби \(\frac{28}{105}\), \(\frac{25}{105}\) и \(\frac{21}{105}\).

Ответ: a) \(\frac{4}{10}\) и \(\frac{3}{10}\); б) \(\frac{3}{18}\) и \(\frac{10}{18}\); в) \(\frac{9}{24}\) и \(\frac{14}{24}\); г) \(\frac{28}{105}\), \(\frac{25}{105}\) и \(\frac{21}{105}\)