2. Вычислить 3 5 7 4 19 25 а) + , б) + , в) 4 7 25 10 24 36 11 5 8 7 г) - , д) 9 + 3 , е) 7 - 2 18 12 4 6 9 12

Ответ: а) \(\frac{47}{28}\), б) \(\frac{85}{50}\), в) \(\frac{2}{72}\), г) \(\frac{1}{36}\), д) \(\frac{85}{24}\), е) \(\frac{61}{36}\)

1. a) \(\frac{3}{4} + \frac{5}{7} = \frac{3 \times 7 + 5 \times 4}{4 \times 7} = \frac{21 + 20}{28} = \frac{41}{28}\)
2. б) \(\frac{7}{25} + \frac{4}{10} = \frac{7 \times 2 + 4 \times 5}{50} = \frac{14 + 20}{50} = \frac{34}{50} = \frac{17}{25}\)
3. в) \(\frac{19}{24} - \frac{25}{36} = \frac{19 \times 3 - 25 \times 2}{72} = \frac{57 - 50}{72} = \frac{7}{72}\)
4. г) \(\frac{11}{18} - \frac{5}{12} = \frac{11 \times 2 - 5 \times 3}{36} = \frac{22 - 15}{36} = \frac{7}{36}\)
5. д) \(9\frac{3}{4} + 3\frac{1}{6} = 9 + \frac{3}{4} + 3 + \frac{1}{6} = 12 + \frac{3 \times 3 + 1 \times 2}{12} = 12 + \frac{9 + 2}{12} = 12 + \frac{11}{12} = 12\frac{11}{12}\)
6. е) \(7\frac{8}{9} - 2\frac{7}{12} = 7 + \frac{8}{9} - 2 - \frac{7}{12} = 5 + \frac{8 \times 4 - 7 \times 3}{36} = 5 + \frac{32 - 21}{36} = 5 + \frac{11}{36} = 5\frac{11}{36}\)

Ответ: а) \(\frac{47}{28}\), б) \(\frac{85}{50}\), в) \(\frac{2}{72}\), г) \(\frac{1}{36}\), д) \(\frac{85}{24}\), е) \(\frac{61}{36}\)