№23
Вопрос
Номер 1.
Приведите дроби к знаменателю 72.
а) 1/2 (72 ∶ 2 = 36 = 1 · 36/2 · 36 = 36/72 б) 2/3 (24 = 1/2 = 48/72 в) 3/4 (18 = 54/72 г) 5/6 (12 = 60/72 д) 3/8 (9 = 27/72 е) 5/12 (6 = 30/72 ж) 11/18 (4 = 44/72 з) 15/36 (2 = 30/72
1/2
1 · 36/2 · 36
36/72
2/3
1/2
48/72
3/4
54/72
5/6
60/72
3/8
27/72
5/12
30/72
11/18
44/72
15/36
30/72
Вопрос
Номер 2.
Приведите к наименьшему общему знаменателю дроби:
а) 9/20 и 6/35 ; б) 11/14 и 11/42 ; в) 13/12 и 5/9 .
9/20
6/35
11/14
11/42
13/12
5/9
а) 9/20 и 6/35 ; НОК (20, 35) = 140, 9/20 (7 = 9·7/20·7 = 63/140 , 6/35 (4 = 6 · 4/35 · 4 = 24/140 . б) 11/14 и 11/42 ; НОК (14, 21) = 42, 11/14 (3 = 11·3/14·3 = 33/42 , 11/42 (1 = 11 · 1/42 · 1 = 11/42 . в) 13/12 и 5/9 ; НОК (12, 9) = 36, 13/12 (3 = 13·3/12·3 = 39/36 , 5/9 (4 = 5 · 4/9 · 4 = 20/36 .
9/20
6/35
9/20
9·7/20·7
63/140
6/35
6 · 4/35 · 4
24/140
11/14
11/42
11/14
11·3/14·3
33/42
11/42
11 · 1/42 · 1
11/42
13/12
5/9
13/12
13·3/12·3
39/36
5/9
5 · 4/9 · 4
20/36
