Задание 1. Найдите значение выражения 1) (1/12 - 17/15)*10/3; 2) (7/15 + 19/30)*9/11; 3) (3/25 - 2/35)*14; 4) (1/30 + 7/10)*6

Решение:

1. \( \left( \frac{1}{12} - \frac{17}{15} \right) \cdot \frac{10}{3} = \left( \frac{5}{60} - \frac{68}{60} \right) \cdot \frac{10}{3} = \left( -\frac{63}{60} \right) \cdot \frac{10}{3} = -\frac{63}{60} \cdot \frac{10}{3} = -\frac{63 \cdot 10}{60 \cdot 3} = -\frac{21 \cdot 10}{20 \cdot 3} = -\frac{7 \cdot 10}{20} = -\frac{7}{2} = -3.5 \)
2. \( \left( \frac{7}{15} + \frac{19}{30} \right) \cdot \frac{9}{11} = \left( \frac{14}{30} + \frac{19}{30} \right) \cdot \frac{9}{11} = \frac{33}{30} \cdot \frac{9}{11} = \frac{3}{30} \cdot 9 = \frac{1}{10} \cdot 9 = \frac{9}{10} = 0.9 \)
3. \( \left( \frac{3}{25} - \frac{2}{35} \right) \cdot 14 = \left( \frac{21}{175} - \frac{10}{175} \right) \cdot 14 = \frac{11}{175} \cdot 14 = \frac{11 \cdot 14}{175} = \frac{11 \cdot 2 \cdot 7}{25 \cdot 7} = \frac{22}{25} = 0.88 \)
4. \( \left( \frac{1}{30} + \frac{7}{10} \right) \cdot 6 = \left( \frac{1}{30} + \frac{21}{30} \right) \cdot 6 = \frac{22}{30} \cdot 6 = \frac{22}{5} = 4.4 \)

Ответ: 1) -3.5; 2) 0.9; 3) 0.88; 4) 4.4.