13. Тип 2.1 № 1869 Вычислите: 7 39 (11 14 1 6)

Решение:

1. \[ \frac{11}{14} - \frac{1}{6} = \frac{11 \times 3 - 1 \times 7}{42} = \frac{33 - 7}{42} = \frac{26}{42} = \frac{13}{21} \]
2. \[ \frac{7}{39} \times \frac{13}{21} = \frac{7 \times 13}{39 \times 21} = \frac{7 \times 13}{3 \times 13 \times 3 \times 7} = \frac{1}{3 \times 3} = \frac{1}{9} \]

Ответ: 1/9