Выполни действие при меняя распределительный закон умножения. 7/12*4/21+5/12*4/21=. 2 цел2/17*1 цел5/6 минус1 цел5/6*1 цел2/17. (. (3 цел4/15+4 цел5/6) * (3 цел17/18 минус2 цел5/9) =

а) 7/12 * 4/21 + 5/12 * 4/21 = 4/21 * (7/12 + 5/12) = 4/21 * 1 = 4/21.

б) 2 2/17 * 1 5/6 - 1 5/6 * 1 2/17 = 36/17 * (11/6 - 11/6) = 36/17 * 0 = 0.

2 2/17 = (2 * 17 + 2) / 17 = 36/17.

1 5/6 = (1 * 6 + 5) / 6 = 11/6.

в) (3 4/15 + 4 5/6) * (3 17/18 - 2 5/9) = 11 1/4.

3 4/15 = (3 * 15 + 4) / 15 = 49/15.

4 5/6 = (4 * 6 + 5) / 6 = 29/6.

3 17/18 = (3 * 18 + 17) / 18 = 71/18.

2 5/9 = (2 * 9 + 5) / 9 = 23/9.

1. 49/15 + 29/6 = (98 + 145) / 30 = 243/30 сократим на 3 = 81/10.

2. 71/18 - 23/9 = (71 - 46) / 18 = 25/18.

3. 81/10 * 25/18 = (81 * 25) / (10 * 18) = 2025/180 сократим на 45 = 45/4 = 11 1/4.