1. Выполните умножение: 1) 7/16 * 8/49; 2) 4/7 * 8/9; 3) 56/69 * 69/77; 4) 55/72 * 40/99.

Решение:

1. \( \frac{7}{16} \cdot \frac{8}{49} = \frac{7 \cdot 8}{16 \cdot 49} = \frac{7 \cdot 8}{(2 \cdot 8) \cdot (7 \cdot 7)} = \frac{1}{2 \cdot 7} = \frac{1}{14} \)
2. \( \frac{4}{7} \cdot \frac{8}{9} = \frac{4 \cdot 8}{7 \cdot 9} = \frac{32}{63} \)
3. \( \frac{56}{69} \cdot \frac{69}{77} = \frac{56 \cdot 69}{69 \cdot 77} = \frac{56}{77} = \frac{8 \cdot 7}{11 \cdot 7} = \frac{8}{11} \)
4. \( \frac{55}{72} \cdot \frac{40}{99} = \frac{55 \cdot 40}{72 \cdot 99} = \frac{(5 \cdot 11) \cdot (5 \cdot 8)}{(9 \cdot 8) \cdot (9 \cdot 11)} = \frac{5 \cdot 5}{9 \cdot 9} = \frac{25}{81} \)

Ответ: 1) 1/14; 2) 32/63; 3) 8/11; 4) 25/81.