9/5 - (7/15-5/12) • (3/14+1/2) =

Question

Анна Сидорова

Математика

1 апреля, 01:22

9/5 - (7/15-5/12) • (3/14+1/2) =

+4

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Das · Answer 1

9/5 - (7/15 - 5/12) * (3/14 + 1/2) = 1 107/140.

1) 7/15 - 5/12 = (7 * 4) / (15 * 4) - (5 * 5) / (12 * 5) = 28/60 - 25/60 = (28 - 25) / 60 = 3/60 = 3 / (3 * 20) = 1/20 (сократили 3 в числителе и знаменателе);

2) 3/14 + 1/2 = 3/14 + (1 * 7) / (2 * 7) = 3/14 + 7/14 = (3 + 7) / 14 = 10/14 = (5 * 2) / (7 * 2) = 5/7;

3) 1/20 * 5/7 = (1 * 5) / (20 * 7) = (1 * 5) / (4 * 5 * 7) = 1 / (4 * 7) = 1/28;

4) 9/5 - 1/28 = (9 * 28) / (5 * 28) - (1 * 5) / (28 * 5) = 252/140 - 5/140 = (252 - 5) / 140 = 247/140 = 1 (247 - 1 * 140) / 140 = 1 (247 - 140) / 140 = 1 107/140.