正负数的计算题+(28)=21
31+(-116)=-85
(96)-56=40
(-72)-(-37)-(-22)-17
解:原式=-72+37+22-17
=-30
(-16)-(-12)-24-(-18)
解:原式=-16+12-24+18
=-10
23-(-76)-36-(-105)
解:原式=23+76-36+105
=168
(-32)-(-27)-(-72)-87
解:原式=-32+27+72-87
=-20
自然数
自然数的减法不是封闭的。除非被减数大于减数才可以是封闭的。例如,26不能被11减。这种情况使用两种方法中的一种: 正负数的计算题+(28)=21
31+(-116)=-85
(96)-56=40
(-72)-(-37)-(-22)-17
解:原式=-72+37+22-17
=-30
(-16)-(-12)-24-(-18)
解:原式=-16+12-24+18
=-10
23-(-76)-36-(-105)
解:原式=23+76-36+105
=168
(-32)-(-27)-(-72)-87
解:原式=-32+27+72-87
=-20
4.某潜艇从海平面以下27米处上升到海平面以下18米处,此潜艇上升了9米
计算:
-2.5+(-5分之1)=-2.7
0.4-(-4分之1)+6分之1=60分之49
3分之-(-6分之5)+3分之2看不懂
3分之1+(-5分之1)+1+3分之2=1.8
27-18+(-7)-32=-30
0.5+(-4分之1)-(-2.75)+2分之1=3.5
33.1-(22.9)+(-10.5)=-0.3
(-8)-(-15)+(-9)-(-12)=10
-3分之2+(-6分之1)-(-4分之1)-2分之1=-12分之1
5分之3-2分之3+(-4分之11)+4分之13=-0.6
7+(-2)-3.4=1.6
-21.6+3-7.4+(-5分之2)=-26.4
31+(-4分之5)+0.25=30
7-(-2分之1)+1.5=9
49-(-20.6)-5分之3=69
(-5分之6)-7-(-3.2)+(-1)=-6
1、-15+6÷(-3)×1/2 2、(1/4-1/2+1/6)×24
3、|-5/14|×(-3/7)2÷3/14 4、2/3+(-1/5)-1+1/3
23+(-73)
(-84)+(-49)
7+(-2.04)
4.23+(-7.57)
(-7/3)+(-7/6)
9/4+(-3/2)
3.75+(2.25)+5/4
-3.75+(+5/4)+(-1.5)
(17/4)+(-10/3)+(+13/3)+(11/3) (2)(-1.8)+(+0.2)+(-1.7)+(0.1)+(+1.8)+(+1.4)
4.6-(-3/4+1.6-4-3/4)
1/2+3+5/6-7/12
[2/3-4-1/4*(-0.4)]/1/3+2
22+(-4)+(-2)+4*3
-2*8-8*1/2+8/1/8
(2/3+1/2)/(-1/12)*(-12)
(-28)/(-6+4)+(-1)
2/(-2)+0/7-(-8)*(-2)
(1/4-5/6+1/3+2/3)/1/2
18-6/(-3)*(-2)
(5+3/8*8/30/(-2)-3
(-84)/2*(-3)/(-6)
1/2*(-4/15)/2/3
-3x+2y-5x-7y
-5+21*8/2-6-59
68/21-8-11*8+61
-2/9-7/9-56
4.6-(-3/4+1.6-4-3/4)
1/2+3+5/6-7/12
[2/3-4-1/4*(-0.4)]/1/3+2
22+(-4)+(-2)+4*3
-2*8-8*1/2+8/1/8
(2/3+1/2)/(-1/12)*(-12)
(-28)/(-6+4)+(-1)
2/(-2)+0/7-(-8)*(-2)
(1/4-5/6+1/3+2/3)/1/2
18-6/(-3)*(-2)
(5+3/8*8/30/(-2)-3
(-84)/2*(-3)/(-6)
1/2*(-4/15)/2/3
-3x+2y-5x-7y
-5+21*8/2-6-59
68/21-8-11*8+61
-2/9-7/9-56
4.6-(-3/4+1.6-4-3/4)
1/2+3+5/6-7/12
[2/3-4-1/4*(-0.4)]/1/3+2
22+(-4)+(-2)+4*3
-2*8-8*1/2+8/1/8
(2/3+1/2)/(-1/12)*(-12)
(-28)/(-6+4)+(-1)
2/(-2)+0/7-(-8)*(-2)
(1/4-5/6+1/3+2/3)/1/2
18-6/(-3)*(-2)
(5+3/8*8/30/(-2)-3
(-84)/2*(-3)/(-6)
1/2*(-4/15)/2/3
-3x+2y-5x-7y
-1+2-3+4-5+6-7;
50-28+(-24)-(-22);
19.8-(-20.3)-(+20.2)-10.8;
0.25- +(-1 )-(+3 ).
-1-23.33-(+76.76);
1-2*2*2*2;
(-6-24.3)-(-12+9.1)+(0-2.1);
-1+8-7
(1) (2) 12—(—18)+(—7)—15
(3) (4) -2 +|5-8|+24÷(-3)
26. -0.5÷ =( )
27. -15÷ ×(-5)=( )
28. -32 + (-2) 2 =( )
23+(-73)
(-84)+(-49)
7+(-2.04)
4.23+(-7.57)
(-7/3)+(-7/6)
9/4+(-3/2)
3.75+(2.25)+5/4
-3.75+(+5/4)+(-1.5)
(17/4)+(-10/3)+(+13/3)+(11/3)
(-1.8)+(+0.2)+(-1.7)+(0.1)+(+1.8)+(+1.4)
4.6-(-3/4+1.6-4-3/4)
1/2+3+5/6-7/12
[2/3-4-1/4*(-0.4)]/1/3+2
22+(-4)+(-2)+4*3
-2*8-8*1/2+8/1/8
(2/3+1/2)/(-1/12)*(-12)
(-28)/(-6+4)+(-1)
2/(-2)+0/7-(-8)*(-2)
(1/4-5/6+1/3+2/3)/1/2
18-6/(-3)*(-2)
(5+3/8*8/30/(-2)-3
(-84)/2*(-3)/(-6)
1/2*(-4/15)/2/3
-3x+2y-5x-7y
-5+21*8/2-6-59
68/21-8-11*8+61
-2/9-7/9-56
4.6-(-3/4+1.6-4-3/4)
1/2+3+5/6-7/12
[2/3-4-1/4*(-0.4)]/1/3+2
22+(-4)+(-2)+4*3
-2*8-8*1/2+8/1/8
(2/3+1/2)/(-1/12)*(-12)
(-28)/(-6+4)+(-1)
2/(-2)+0/7-(-8)*(-2)
(1/4-5/6+1/3+2/3)/1/2
18-6/(-3)*(-2)
(5+3/8*8/30/(-2)-3
(-84)/2*(-3)/(-6)
1/2*(-4/15)/2/3
-3x+2y-5x-7y
-5+21*8/2-6-59
68/21-8-11*8+61
-2/9-7/9-56
4.6-(-3/4+1.6-4-3/4)
1/2+3+5/6-7/12
[2/3-4-1/4*(-0.4)]/1/3+2
22+(-4)+(-2)+4*3
-2*8-8*1/2+8/1/8
(2/3+1/2)/(-1/12)*(-12)
(-28)/(-6+4)+(-1)
2/(-2)+0/7-(-8)*(-2)
(1/4-5/6+1/3+2/3)/1/2
18-6/(-3)*(-2)
(5+3/8*8/30/(-2)-3
(-84)/2*(-3)/(-6)
1/2*(-4/15)/2/3
-3x+2y-5x-7y
-1+2-3+4-5+6-7;
50-28+(-24)-(-22);
19.8-(-20.3)-(+20.2)-10.8;
0.25- +(-1 )-(+3 ).
-1-23.33-(+76.76);
1-2*2*2*2;
(-6-24.3)-(-12+9.1)+(0-2.1);
-1+8-7 )23+(-73)
(2)(-84)+(-49)
(3)7+(-2.04)
(4)4.23+(-7.57)
(5)(-7/3)+(-7/6)
(6)9/4+(-3/2)
(7)3.75+(2.25)+5/4
(8)-3.75+(+5/4)+(-1.5)
(9)(-17/4)+(-10/3)+(+13/3)+(11/3)
(10)(-1.8)+(+0.2)+(-1.7)+(0.1)+(+1.8)+(+1.4)
(11)(+1.3)-(+17/7)
(12)(-2)-(+2/3)
(13)|(-7.2)-(-6.3)+(1.1)|
(14)|(-5/4)-(-3/4)|-|1-5/4-|-3/4|)
(15)(-2/199)*(-7/6-3/2+8/3)
(16)4a)*(-3b)*(5c)*1/6
还有50道题,不过没有答案
1. 3/7 × 49/9 - 4/3
2. 8/9 × 15/36 + 1/27
3. 12× 5/6 – 2/9 ×3
4. 8× 5/4 + 1/4
5. 6÷ 3/8 – 3/8 ÷6
6. 4/7 × 5/9 + 3/7 × 5/9
7. 5/2 -( 3/2 + 4/5 )
8. 7/8 + ( 1/8 + 1/9 )
9. 9 × 5/6 + 5/6
10. 3/4 × 8/9 - 1/3
0.12χ+1.8×0.9=7.2 (9-5χ)×0.3=1.02 6.4χ-χ=28+4.4
11. 7 × 5/49 + 3/14
12. 6 ×( 1/2 + 2/3 )
13. 8 × 4/5 + 8 × 11/5
14. 31 × 5/6 – 5/6
15. 9/7 - ( 2/7 – 10/21 )
16. 5/9 × 18 – 14 × 2/7
17. 4/5 × 25/16 + 2/3 × 3/4
18. 14 × 8/7 – 5/6 × 12/15
19. 17/32 – 3/4 × 9/24
20. 3 × 2/9 + 1/3
21. 5/7 × 3/25 + 3/7
22. 3/14 ×× 2/3 + 1/6
23. 1/5 × 2/3 + 5/6
24. 9/22 + 1/11 ÷ 1/2
25. 5/3 × 11/5 + 4/3
26. 45 × 2/3 + 1/3 × 15
27. 7/19 + 12/19 × 5/6
28. 1/4 + 3/4 ÷ 2/3
29. 8/7 × 21/16 + 1/2
30. 101 × 1/5 – 1/5 × 21
31.50+160÷40 (58+370)÷(64-45)
32.120-144÷18+35
33.347+45×2-4160÷52
34(58+37)÷(64-9×5)
35.95÷(64-45)
36.178-145÷5×6+42 420+580-64×21÷28
37.812-700÷(9+31×11) (136+64)×(65-345÷23)
38.85+14×(14+208÷26)
39.(284+16)×(512-8208÷18)
40.120-36×4÷18+35
41.(58+37)÷(64-9×5)
42.(6.8-6.8×0.55)÷8.5
43.0.12× 4.8÷0.12×4.8
44.(3.2×1.5+2.5)÷1.6 (2)3.2×(1.5+2.5)÷1.6
45.6-1.6÷4= 5.38+7.85-5.37=
46.7.2÷0.8-1.2×5= 6-1.19×3-0.43=
47.6.5×(4.8-1.2×4)= 0.68×1.9+0.32×1.9
48.10.15-10.75×0.4-5.7
49.5.8×(3.87-0.13)+4.2×3.74
50.32.52-(6+9.728÷3.2)×2.5
51.-5+58+13+90+78-(-56)+50
52.-7*2-57/(3
53.(-7)*2/(1/3)+79/(3+6/4)
54.123+456+789+98/(-4)
55.369/33-(-54-31/15.5)
56.39+{3x[42/2x(3x8)]}
57.9x8x7/5x(4+6)
58.11x22/(4+12/2)
59.94+(-60)/10 混合运算时要先算乘方再算乘除再算加减
1.)(1/3 + 1/4 - 1/6)X 24=(7/12-1/6)X24=5/12X24=10.
2)、(-4)X(-5)X 0.25=20X0.25=5
3)、100 X (-3)X (-5)X 0.01=(-300)X(-5)X0.01=1500X0.01=15
4)、(1/9 - 1/6 - 1/18)X 36=(-1/18-1/18)X36=-1/9X36=-4
5)、(1/4 - 1/2 - 1/8)X 128=(-1/4-1/8)X128=-3/8X128=-48
6)、{9 X (-4)} X (-1/4)=(-36)X(-1/4)=9
7)、2.25 X (-2.3)X 3/25=-5.175X3/25=-0.621
8)、(-2.1)X 6.5 X (-3/7)=-13.65X(-3/7)=5.85
(1) 66x+17y=396725x+y=1200 答案:x=48 y=47 (2) 18x+23y=2303 74x-y=1998 答案:x=27 y=79 (3) 44x+90y=7796 44x+y=3476 答案:x=79 y=48 (4) 76x-66y=4082 30x-y=2940 答案:x=98 y=51 (5) 67x+54y=8546 71x-y=56...
正负数的计算题+(28)=21
31+(-116)=-85
(96)-56=40
(-72)-(-37)-(-22)-17
解:原式=-72+37+22-17
=-30
(-16)-(-12)-24-(-18)
解:原式=-16+12-24+18
=-10
23-(-76)-36-(-105)
解:原式=23+76-36+105
=168
(-32)-(-27)-(-72)-87
解:原式=-32+27+72-87
=-20
自然数
自然数的减法不是封闭的。除非被减数大于减数才可以是封闭的。例如,26不能被11减。这种情况使用两种方法中的一种: 正负数的计算题+(28)=21
31+(-116)=-85
(96)-56=40
(-72)-(-37)-(-22)-17
解:原式=-72+37+22-17
=-30
(-16)-(-12)-24-(-18)
解:原式=-16+12-24+18
=-10
23-(-76)-36-(-105)
解:原式=23+76-36+105
=168
(-32)-(-27)-(-72)-87
解:原式=-32+27+72-87
=-20
4.某潜艇从海平面以下27米处上升到海平面以下18米处,此潜艇上升了9米
计算:
-2.5+(-5分之1)=-2.7
0.4-(-4分之1)+6分之1=60分之49
3分之-(-6分之5)+3分之2看不懂
3分之1+(-5分之1)+1+3分之2=1.8
27-18+(-7)-32=-30
0.5+(-4分之1)-(-2.75)+2分之1=3.5
33.1-(22.9)+(-10.5)=-0.3
(-8)-(-15)+(-9)-(-12)=10
-3分之2+(-6分之1)-(-4分之1)-2分之1=-12分之1
5分之3-2分之3+(-4分之11)+4分之13=-0.6
7+(-2)-3.4=1.6
-21.6+3-7.4+(-5分之2)=-26.4
31+(-4分之5)+0.25=30
7-(-2分之1)+1.5=9
49-(-20.6)-5分之3=69
(-5分之6)-7-(-3.2)+(-1)=-6
1、-15+6÷(-3)×1/2 2、(1/4-1/2+1/6)×24
3、|-5/14|×(-3/7)2÷3/14 4、2/3+(-1/5)-1+1/3
23+(-73)
(-84)+(-49)
7+(-2.04)
4.23+(-7.57)
(-7/3)+(-7/6)
9/4+(-3/2)
3.75+(2.25)+5/4
-3.75+(+5/4)+(-1.5)
(17/4)+(-10/3)+(+13/3)+(11/3) (2)(-1.8)+(+0.2)+(-1.7)+(0.1)+(+1.8)+(+1.4)
4.6-(-3/4+1.6-4-3/4)
1/2+3+5/6-7/12
[2/3-4-1/4*(-0.4)]/1/3+2
22+(-4)+(-2)+4*3
-2*8-8*1/2+8/1/8
(2/3+1/2)/(-1/12)*(-12)
(-28)/(-6+4)+(-1)
2/(-2)+0/7-(-8)*(-2)
(1/4-5/6+1/3+2/3)/1/2
18-6/(-3)*(-2)
(5+3/8*8/30/(-2)-3
(-84)/2*(-3)/(-6)
1/2*(-4/15)/2/3
-3x+2y-5x-7y
-5+21*8/2-6-59
68/21-8-11*8+61
-2/9-7/9-56
4.6-(-3/4+1.6-4-3/4)
1/2+3+5/6-7/12
[2/3-4-1/4*(-0.4)]/1/3+2
22+(-4)+(-2)+4*3
-2*8-8*1/2+8/1/8
(2/3+1/2)/(-1/12)*(-12)
(-28)/(-6+4)+(-1)
2/(-2)+0/7-(-8)*(-2)
(1/4-5/6+1/3+2/3)/1/2
18-6/(-3)*(-2)
(5+3/8*8/30/(-2)-3
(-84)/2*(-3)/(-6)
1/2*(-4/15)/2/3
-3x+2y-5x-7y
-5+21*8/2-6-59
68/21-8-11*8+61
-2/9-7/9-56
4.6-(-3/4+1.6-4-3/4)
1/2+3+5/6-7/12
[2/3-4-1/4*(-0.4)]/1/3+2
22+(-4)+(-2)+4*3
-2*8-8*1/2+8/1/8
(2/3+1/2)/(-1/12)*(-12)
(-28)/(-6+4)+(-1)
2/(-2)+0/7-(-8)*(-2)
(1/4-5/6+1/3+2/3)/1/2
18-6/(-3)*(-2)
(5+3/8*8/30/(-2)-3
(-84)/2*(-3)/(-6)
1/2*(-4/15)/2/3
-3x+2y-5x-7y
-1+2-3+4-5+6-7;
50-28+(-24)-(-22);
19.8-(-20.3)-(+20.2)-10.8;
0.25- +(-1 )-(+3 ).
-1-23.33-(+76.76);
1-2*2*2*2;
(-6-24.3)-(-12+9.1)+(0-2.1);
-1+8-7
(1) (2) 12—(—18)+(—7)—15
(3) (4) -2 +|5-8|+24÷(-3)
26. -0.5÷ =( )
27. -15÷ ×(-5)=( )
28. -32 + (-2) 2 =( )
23+(-73)
(-84)+(-49)
7+(-2.04)
4.23+(-7.57)
(-7/3)+(-7/6)
9/4+(-3/2)
3.75+(2.25)+5/4
-3.75+(+5/4)+(-1.5)
(17/4)+(-10/3)+(+13/3)+(11/3)
(-1.8)+(+0.2)+(-1.7)+(0.1)+(+1.8)+(+1.4)
4.6-(-3/4+1.6-4-3/4)
1/2+3+5/6-7/12
[2/3-4-1/4*(-0.4)]/1/3+2
22+(-4)+(-2)+4*3
-2*8-8*1/2+8/1/8
(2/3+1/2)/(-1/12)*(-12)
(-28)/(-6+4)+(-1)
2/(-2)+0/7-(-8)*(-2)
(1/4-5/6+1/3+2/3)/1/2
18-6/(-3)*(-2)
(5+3/8*8/30/(-2)-3
(-84)/2*(-3)/(-6)
1/2*(-4/15)/2/3
-3x+2y-5x-7y
-5+21*8/2-6-59
68/21-8-11*8+61
-2/9-7/9-56
4.6-(-3/4+1.6-4-3/4)
1/2+3+5/6-7/12
[2/3-4-1/4*(-0.4)]/1/3+2
22+(-4)+(-2)+4*3
-2*8-8*1/2+8/1/8
(2/3+1/2)/(-1/12)*(-12)
(-28)/(-6+4)+(-1)
2/(-2)+0/7-(-8)*(-2)
(1/4-5/6+1/3+2/3)/1/2
18-6/(-3)*(-2)
(5+3/8*8/30/(-2)-3
(-84)/2*(-3)/(-6)
1/2*(-4/15)/2/3
-3x+2y-5x-7y
-5+21*8/2-6-59
68/21-8-11*8+61
-2/9-7/9-56
4.6-(-3/4+1.6-4-3/4)
1/2+3+5/6-7/12
[2/3-4-1/4*(-0.4)]/1/3+2
22+(-4)+(-2)+4*3
-2*8-8*1/2+8/1/8
(2/3+1/2)/(-1/12)*(-12)
(-28)/(-6+4)+(-1)
2/(-2)+0/7-(-8)*(-2)
(1/4-5/6+1/3+2/3)/1/2
18-6/(-3)*(-2)
(5+3/8*8/30/(-2)-3
(-84)/2*(-3)/(-6)
1/2*(-4/15)/2/3
-3x+2y-5x-7y
-1+2-3+4-5+6-7;
50-28+(-24)-(-22);
19.8-(-20.3)-(+20.2)-10.8;
0.25- +(-1 )-(+3 ).
-1-23.33-(+76.76);
1-2*2*2*2;
(-6-24.3)-(-12+9.1)+(0-2.1);
-1+8-7 )23+(-73)
(2)(-84)+(-49)
(3)7+(-2.04)
(4)4.23+(-7.57)
(5)(-7/3)+(-7/6)
(6)9/4+(-3/2)
(7)3.75+(2.25)+5/4
(8)-3.75+(+5/4)+(-1.5)
(9)(-17/4)+(-10/3)+(+13/3)+(11/3)
(10)(-1.8)+(+0.2)+(-1.7)+(0.1)+(+1.8)+(+1.4)
(11)(+1.3)-(+17/7)
(12)(-2)-(+2/3)
(13)|(-7.2)-(-6.3)+(1.1)|
(14)|(-5/4)-(-3/4)|-|1-5/4-|-3/4|)
(15)(-2/199)*(-7/6-3/2+8/3)
(16)4a)*(-3b)*(5c)*1/6
还有50道题,不过没有答案
1. 3/7 × 49/9 - 4/3
2. 8/9 × 15/36 + 1/27
3. 12× 5/6 – 2/9 ×3
4. 8× 5/4 + 1/4
5. 6÷ 3/8 – 3/8 ÷6
6. 4/7 × 5/9 + 3/7 × 5/9
7. 5/2 -( 3/2 + 4/5 )
8. 7/8 + ( 1/8 + 1/9 )
9. 9 × 5/6 + 5/6
10. 3/4 × 8/9 - 1/3
0.12χ+1.8×0.9=7.2 (9-5χ)×0.3=1.02 6.4χ-χ=28+4.4
11. 7 × 5/49 + 3/14
12. 6 ×( 1/2 + 2/3 )
13. 8 × 4/5 + 8 × 11/5
14. 31 × 5/6 – 5/6
15. 9/7 - ( 2/7 – 10/21 )
16. 5/9 × 18 – 14 × 2/7
17. 4/5 × 25/16 + 2/3 × 3/4
18. 14 × 8/7 – 5/6 × 12/15
19. 17/32 – 3/4 × 9/24
20. 3 × 2/9 + 1/3
21. 5/7 × 3/25 + 3/7
22. 3/14 ×× 2/3 + 1/6
23. 1/5 × 2/3 + 5/6
24. 9/22 + 1/11 ÷ 1/2
25. 5/3 × 11/5 + 4/3
26. 45 × 2/3 + 1/3 × 15
27. 7/19 + 12/19 × 5/6
28. 1/4 + 3/4 ÷ 2/3
29. 8/7 × 21/16 + 1/2
30. 101 × 1/5 – 1/5 × 21
31.50+160÷40 (58+370)÷(64-45)
32.120-144÷18+35
33.347+45×2-4160÷52
34(58+37)÷(64-9×5)
35.95÷(64-45)
36.178-145÷5×6+42 420+580-64×21÷28
37.812-700÷(9+31×11) (136+64)×(65-345÷23)
38.85+14×(14+208÷26)
39.(284+16)×(512-8208÷18)
40.120-36×4÷18+35
41.(58+37)÷(64-9×5)
42.(6.8-6.8×0.55)÷8.5
43.0.12× 4.8÷0.12×4.8
44.(3.2×1.5+2.5)÷1.6 (2)3.2×(1.5+2.5)÷1.6
45.6-1.6÷4= 5.38+7.85-5.37=
46.7.2÷0.8-1.2×5= 6-1.19×3-0.43=
47.6.5×(4.8-1.2×4)= 0.68×1.9+0.32×1.9
48.10.15-10.75×0.4-5.7
49.5.8×(3.87-0.13)+4.2×3.74
50.32.52-(6+9.728÷3.2)×2.5
51.-5+58+13+90+78-(-56)+50
52.-7*2-57/(3
53.(-7)*2/(1/3)+79/(3+6/4)
54.123+456+789+98/(-4)
55.369/33-(-54-31/15.5)
56.39+{3x[42/2x(3x8)]}
57.9x8x7/5x(4+6)
58.11x22/(4+12/2)
59.94+(-60)/10 混合运算时要先算乘方再算乘除再算加减
1.)(1/3 + 1/4 - 1/6)X 24=(7/12-1/6)X24=5/12X24=10.
2)、(-4)X(-5)X 0.25=20X0.25=5
3)、100 X (-3)X (-5)X 0.01=(-300)X(-5)X0.01=1500X0.01=15
4)、(1/9 - 1/6 - 1/18)X 36=(-1/18-1/18)X36=-1/9X36=-4
5)、(1/4 - 1/2 - 1/8)X 128=(-1/4-1/8)X128=-3/8X128=-48
6)、{9 X (-4)} X (-1/4)=(-36)X(-1/4)=9
7)、2.25 X (-2.3)X 3/25=-5.175X3/25=-0.621
8)、(-2.1)X 6.5 X (-3/7)=-13.65X(-3/7)=5.85
(1) 66x+17y=396725x+y=1200 答案:x=48 y=47 (2) 18x+23y=2303 74x-y=1998 答案:x=27 y=79 (3) 44x+90y=7796 44x+y=3476 答案:x=79 y=48 (4) 76x-66y=4082 30x-y=2940 答案:x=98 y=51 (5) 67x+54y=8546 71x-y=56...