Задание 1.
1) - 6,2 • 3,4 = - 21,08 ;
2) - 6 целых 3/4 • ( - 1 целая 11/45 ) = 27/4 • 56/45 = 1512/80 = 42/5 = 8 целых 2/8 ;
3) - 19,68 : ( - 0,8 ) = 15,8 ;
4) 16,32 : ( - 16 ) = - 1,02 ;
Задание 2.
1) - 2,4а • ( - 5b ) = 12ab ;
2) 9a - a - 8b + 3b = 8a - 5b ;
3) a + ( a - 10 ) - ( 15 + a ) = a + a - 10 - 15 - a =
a - 25 ;
4) - 4 ( b - 4 ) + 7 ( b + 2 ) = - 4b + 16 + 7b + 14 =
3b + 30 ;
Задание 3.
( - 3,25 - ( -1,75 ) ) : ( - 0,6 ) + 0,8 • ( - 7 )
решаем по действиям :
1) - 3,25 - ( - 1,75 ) = - ( 3,25 - 1,75 ) = - 1,5 ;
2) 0,8 • ( - 7 ) = - 0,8 • 7 = - 5,6 ;
3) - 1,5 : ( - 0,6 ) = 15/6 = 5/2 = 2 целых 1/2 ;
4) 2 целых 1/2 + ( - 5,6 ) = 2 целых 1/2 - 5/6 =
2 целых 1/2 - 5 целых 6/10 = 5/2 - 56/10 = 25/10 - 56/10 = - 31/10 = - 3 целых 1/10 ;
Задание 4.
- 0,6 ( 1,6b - 5 ) - ( 2,9 - 8 ) - 4 ( 4 - 1,5b )
- 0,96b + 3 - 2,9 + 8 - 16 + 6b =
5,04b - 7,9 , при b = - 9/13
5,04 • ( - 9/13 ) - 7,9 = - 11 целых 253/650 ;
1) 7 7/9 - 4 1/12 = 7 28/36 - 4 3/36 = 3 25/36
2) 3 25/36 + 2 3/4 = 3 25/36 + 2 27/36 = 5 + 52/36=
= 5+ 13/9 = 5 + 1 4/9 = 6 4/9
17 2/3 - 6 1/36 + 4 3/8 = 16 1/72
1) 17 2/3 - 6 1/36 = 17 24/36 - 6 1/36 = 11 23/36
2) 11 23/36 + 4 3/8 = 11 46/72 + 4 27/72 = 15 + 73/72=
=15 + 1 1/72 = 16 1/72
10 9/16 - (3 11/12 + 4 4/9 ) = 2 29/144
1) 3 11/12 + 4 4/9 = 3 33/36 + 4 16/36 = 7 + 49/36=
= 7 + 1 13/36 = 8 13/36
2)10 9/16 - 8 13 /36 = 10 81/144 - 8 52/144 = 2 29/144
(20 - 7 23/36) - (14 4/27 - 6 1/18) = 4 29/108
1) 20 - 7 23/36 = 12 13/36
2) 14 4/27 - 6 1/18 = 14 8/54 - 6 3/54 = 8 5/54
3) 12 13/36 - 8 5/54 = 12 39/108 - 8 10/108= 4 29/108