№25
Вопрос
Номер 3.
Найдите разность.
а) 5/12 – 2/15 ; НОК (12, 15) = 60, 5/12 (5 – 2/15 (4 = 25 – 8/60 = 17/60 . б) 23/30 – 7/20 ; НОК (30, 20) = 60, 23/30 (2 – 7/20 (3 = 46 – 21/60 = 25/60 . в) 9/10 – 28/45 ; НОК (10, 45) = 90, 9/10 (9 – 28/45 (2 = 81 – 56/90 = 25/90 .
5/12
2/15
5/12
2/15
25 – 8/60
17/60
23/30
7/20
23/30
7/20
46 – 21/60
25/60
9/10
28/45
9/10
28/45
81 – 56/90
25/90
Вопрос
Номер 1.
Найдите сумму.
а) 1 7/12 + 3 9/16 ; НОК (12, 16) = 48 ; 1 7/12 + 3 9/16 = 1 + 7/12 + 3 + 9/16 = (1 + 3) +( 7/12 (4 + 9/16 (3 ) = 4 + 28 + 27/48 = 4 + 55/48 = 4 + 1 7/48 = 5 7/48 . б) 2 3/4 + 4 5/14 ; НОК (4, 14) = 28 ; 2 3/4 + 4 5/14 = 2 + 3/4 + 4 + 5 5/14 = (2 + 4) + ( 3/4 (7 + 5/14 (2 )= 6 + 21 + 10/28 = 6 + 31/28 = 6 + 1 3/28 = 7 3/28 .
7/12
9/16
7/12
9/16
7/12
9/16
7/12
9/16
28 + 27/48
55/48
7/48
3/4
5/14
3/4
5/14
3/4
5/14
3/4
5/14
21 + 10/28
31/28
3/28
