五年级下册数学天天练答案
发布时间:2019-10-28 14:33:44
发布时间:2019-10-28 14:33:44
《五年级口算、速算天天练》参考答案34-50 34、观察物体
720+180 = 900 0.36÷4 = 0.09 7.8×5×2 = 78
298×2 = 596 4.2-0.8 = 3.4 320×50÷25 = 640
0.8×3 = 2.4 4.6÷2 = 2.3 0.125×5.9×8 = 5.9
0.4×300 = 120 0.46÷2 = 0.23 21×45÷7 = 135
0.6×0.6 = 0.36 8.8÷4 = 2.2 2.8+1.6+0.4 = 4.8
0.5×101 = 50.5 72×125 = 9000 5×7+39 = 74
0.84÷6 = 0.14 3.81×2 = 7.62 0.125×15×8 = 15
123×5 = 615 0.4×200 = 80 2.5×44 = 110
5.4÷0.9 = 6 9.6×0.5 = 4.8 0.6×0.5×30 = 9
0.8÷0.2 = 4 2.45÷0.01 = 245 17×28+28×83 = 2800
0×4.25 = 0 50×3.2 = 160 54-32.4-16.6 = 5
695-474 = 221 52×99 = 5148 15×4×0.7 = 42
0.32÷0.32 = 1 4.8×3 = 14.4 99×0.61+0.61 = 61
0.25×2 = 0.5 7.2×5 = 36 1.2÷0.2×50 = 300
3.25×4 = 13 0.35×100 = 35 1.25×32×25 = 1000
0÷6.48 = 0 0.63÷30 = 0.021 2.4×(5+5) = 24
63×90 = 5670 4.5×0.1 = 0.45 13×25×4 = 1300
3.2÷4 = 0.8 324÷100 = 3.24 1300-700+500 = 1100
308-48 = 260 7×0.6 = 4.2 420÷6÷7 = 10
24×25 = 600 1.24×4 = 4.96 43×4×5 = 860
数奥同步学答案
右图(略)中有 60 个长方形(应为“矩形”,否则总数中应减去正方形个数)。
(4+3+2+1) × (3+2+1) = 60 (个)
练29 三、观察物体
0.42÷0.07 = 6 0.5×101 = 50.5 0.48+3.52-3 = 1
52×99 = 5148 9.6×0.5 = 4.8 9×0.4÷6 = 0.6
0.63÷30 = 0.021 7.3÷7.3 = 1 63×30÷30 = 63
30×3.5 = 105 324÷100 = 3.24 30÷0.1÷60 = 5
5.4÷0.9 = 6 7×0.6 = 4.2 4.2-3.6+0.4 = 1
0.35×100 = 35 69.1-47.4 = 21.7 120×25÷5 = 600
7.8×6 = 46.8 4.8×3 = 14.4 6.5÷5×4 = 5.2
1.5×9.9 = 14.85 0.36÷4 = 0.09 1.8×15÷3 = 9
4.5×0.1 = 0.45 123×5 = 615 (0.17-0.09)÷0.2 = 0.4
3.8×9.9 = 37.62 24×25 = 600 6.28+3.72+10 = 20
0.84÷6 = 0.14 72×125 = 9000 2.5×32×1.25 = 100
0.35×100 = 35 0.6×0.6 = 0.36 6×0.14÷3 = 0.28
4.2-0.8 = 3.4 1.24×4 = 4.96 6×3.1÷20 = 0.93
7×0.6 = 4.2 3.25×4 = 13 45×30÷5 = 270
0.8×3 = 2.4 8.8÷4 = 2.2 4.2×20÷6 = 14
4.6÷2 = 2.3 0.25×2 = 0.5 50×0.04×0.1 = 0.2
4.5×0.1 = 0.45 50×3.2 = 160 3.6+6.4+7 = 17
0×4.25 = 0 3.81×2 = 7.62 12.5×0.8×10 = 100
0.46÷2 = 0.23 0.4×200 = 80 0.42×200÷4 = 21
3.2×4 = 12.8 63×90 = 5670 10+7.84+19 = 36.84
数奥同步学答案
图(略),正方体的六个面上A、B、C、D、E、F排列顺序完全相同,那么A的对面是 D ,B的对面是 F ,C的对面是 E 。
从图上可知A与B、C、E、F相邻,故A的对面只能是D;再根据相对方位可以推出E、F的位置。
练30 三、观察物体
2.45÷0.01 = 245 4×250 = 1000 4.26×10÷2.13 = 20
20-7.6 = 12.4 26×9.9 = 257.4 2.4÷0.24+1 = 11
9.8+9.9 = 19.7 4×0.02 = 0.08 4.5×7.8÷7.8 = 4.5
4.3×101 = 434.3 2÷5 = 0.4 4.5÷9×0.5 = 0.25
36÷600 = 0.06 4.8÷0.08 = 60 5×(0.4+0.8) = 6
4.8×5 = 24 4.8÷0.08 = 300 3.26×10÷2 = 16.3
425-199 = 226 15.7-3.7 = 12 40×32÷20 = 64
4.8+3.9 = 8.7 1÷4 = 0.25 48×5-200 = 40
920-105 = 815 4.5×101 = 454.5 0.54×9÷3 = 1.62
1.9×8 = 15.2 3.45+0.55 = 4 6.3÷3.5×3.5 = 6.3
3.21+2.29 = 5.5 30÷60 = 0.5 2.05×9+2.05 = 20.5
5.77-3.66 = 2.11 7.8+2.2 = 10 7.8×99+7.8 = 780
30×3.5 = 105 4.9+7.1 = 12 36×12×0.5 = 216
523-275 = 248 2.7×30 = 81 4.5×101-4.5 = 450
0.32÷0.08 = 4 13×0.5 = 6.5 3.4-0.6-0.4 = 2.4
7.8÷6 = 1.3 9.8+8.7 = 18.5 0.6+5.4÷6 = 1.5
604÷4 = 151 7.8÷3 = 2.6 50.6-24-16 = 10.6
4×1.2 = 4.8 50.5-22.7 = 27.8 3.42-2.48+6.58 = 7.52
0.84÷6 = 0.14 18.3-16.4 = 1.9 418-52×4 = 210
4.7-3.9 = 0.8 0.6×0.12 = 0.072 1.36+5.4+0.64 = 7.4
数奥同步学答案
图(略),正方体的六个面上分别写有A、B、C、D、E五个字母,其中有两个面字母相同,根据下面的三个视图,可以断定 C 被写了两遍。
从图上可知A与B、C、E、F相邻,故A的对面只能是D;再根据相对方位可以推出E、F的位置。
练31 三、观察物体
0.125×8 = 1 2.8÷0.04 = 70 0.63÷0.9-0.5 = 0.2
4.9-1.9 = 3 6.44+7.42 = 13.86 19.9-7.9+2.5 = 14.5
4×0.02 = 0.08 1.48+0.26 = 1.74 51×101-51 = 5100
3.4×100 = 340 0.4×0.5 = 0.2 4÷5+4.6 = 5.4
5.4÷0.06 = 90 1.6×2.5 = 4 329-108-129 = 92
7.2÷0.08 = 90 9.9÷0.3 = 33 4.7×99+4.7 = 470
6.24÷1.04 = 6 5.77+4.68 = 10.45 6×600÷90 = 40
5.4÷0.9 = 6 42-4.2 = 37.8 0.36×5÷4 = 0.45
304÷4 = 76 36.5-24.1 = 12.4 9.3÷3×2 = 6.2
47.6÷2 = 23.8 45×1.1 = 49.5 27×4+27×16 = 540
14.5-3.7 = 10.8 9.04-8.42 = 0.62 7.2÷4.5÷2 = 0.8
12.6-0.6 = 12 780÷30 = 26 0.5×40×1.3 = 26
84÷4 = 21 570÷30 = 19 0.9×0.4×5 = 1.8
506-109 = 397 9÷0.03 = 300 0.04÷0.08-0.4 = 0.1
950-280 = 670 10-6.4 = 3.6 1.25×7.6×8 = 76
740-180 = 560 56÷80 = 0.7 5.6×101-5.6 = 560
700-238 = 462 40÷0.01 = 4000 65.8-39.9-10.1 = 15.8
24.5×0.1 = 2.45 70÷10 = 7 18.3÷2÷5 = 1.83
3.4-1.8 = 1.6 6.3+1.8 = 8.1 700-620+305 = 385
92.7-82.3 = 10.4 41×99 = 4059 4.5×2÷5 = 1.8
数奥同步学答案
图(略),在正方体的八个顶点中选出四个,使它们中的任何三个构成的三角形都是等边三角形。
等边三角形的三边等长,从图上可知这个边长应该是任一面上的对角线。
因此四点组合有:ACFH以及DBEC。
练32 四、简易方程
1、 设长方形的长是a,宽是b,周长为C,面积为S,那么:
周长公式:C=(a+b)×2 面积公式:S=a×b
2、 设正方形的边长是a,周长为C,面积为S,那么:
周长公式:C=4a 面积公式:S=a2
3、 设路程为s,速度为v,时间为t,那路程、时间、速度之间的关系用字母可表示为 s=vt 。
4.5+15.5 = 20 252÷4 = 63 4.8-0.4-0.6 = 3.8
3.7×3 = 11.1 4.8÷0.6 = 8 0.48÷8×10 = 0.6
4.8×5 = 24 21×90 = 1890 54-35.2-4.8 = 14
4.8÷4 = 1.2 9.8×5 = 49 0.8×0.5+4 = 4.4
0.8+1.4 = 2.2 58×0.6 = 34.8 4.8÷6÷0.8 = 1
7.6×4 = 30.4 24-15.2 = 8.8 2.4÷6÷0.2 = 2
240+190 = 430 1.3+0.9 = 2.2 1.4×20×0.5 = 14
69×30 = 2070 4.2+0.6 = 4.8 0.25×4.32×4 = 4.32
10-7.2 = 2.8 88×1.1 = 96.8 2.5×1.73×4 = 17.3
15.9-2.7 = 13.2 8.9-6.8 = 2.1 0.3÷0.15÷4 = 0.5
17.4+32.6 = 50 23.2-18.4 = 4.8 12.5+56.2-60 = 8.7
186÷4 = 46.5 5.6×99 = 554.4 9.26×1.25×8 = 92.6
32.5÷5 = 6.5 3.6×2.5×0.4 = 3.6 18×9.9 = 178.2
24×9.9 = 237.6 2.8÷0.4 = 7 2.5×24×4 = 240
数奥同步学答案
在下题的方格中填上一个合适的数,使等式成立。
[(cb684a72b26de1320fb347842b83d961.png
(9×9+9)÷9-9=1
练33 四、简易方程
省略乘号写出下面各式
a×x= ax b×8 = 8b 12 = 1
x×x = x2 b×1 = 1b 22 = 4
3×a = 3a c·9 = 9c 32 = 9
x×4 = 4x 5·q = 5q 42 = 16
a×b = ab 7·k = 7k 52 = 25
a×8 = 8a 12·c = 12c 62 = 36
b×b = b2 3·a = 3a 72 = 49
a×1 = 1a 1×c = 1c 82 = 64
4×a = 4a 1·b = 1b 92 = 81
t×8 = 8t 5·d = 5d 102 = 100
a·c = ac 6·k = 6k 112 = 121
s·t = st 7·k = 7k 122 = 144
8·a = 8a x·6 = 6x 132 = 169
x·8 = 8x z·9 = 9z 142 = 196
a·5 = 5a y·10 = 10y 152 = 225
b·10 = 10b 8×x = 8x 162 = 256
8·c = 8c a×2 = 2a 172 = 289
12·b = 12b 6×r = 6r 182 = 324
5·c = 5c 8×y = 8y 192 = 361
202 = 400
数奥同步学答案
规定 a*b=a+(a+1)+(a+2)+…(a+b+1) (a、b均为自然数b>a)。如果
a*10=72,a= 2.7 。
72=10a+(1+2+3+4+5+6+7+8+9)=10a+45
10a=72-45=27 a=2.7
练34 四、简易方程
3x+6x= 9x 12x+1.2x = 13.2x 3x+4x+3x = 10x
b+4b = 5b 4.2t-t = 3.2t 4.8x+x+1.2x = 7x
x+x = 2x 1.5a-0.9a = 0.6a 7x+4x-5x = 6x
18x-9x = 9x 7.8x+2.2x = 10x b-0.3b = 0.7b
x×2 = 2x 9a-6a = 3a 6x-3x+2x = 5x
7b-7b = 0 3.6a+4.4a = 8a 9x-5x = 4x
3x+4.5x = 7.5x 17x+14x = 31x 7.2x-2.2x = 5x
7b-4b = 3b 9.05t-2.15t = 6.9t 3.7x+6.5x = 10.2x
5.2a-3.2a = 2a 3.5b+b = 4.5b a+4a = 5a
x+5x = 6x 1.7x-1.4x = 0.3x 3.6x-1.2x = 2.4x
4.5a-2.1a = 2.4a 8.6x-5x = 3.6x 7.2x-4.2x = 3x
18x-14x = 4x 4.8b+3.2b = 8b 7.8t-5.3t = 2.5t
15b-7.5b = 7.5b 5b+3b = 8b 3.2x+4.8x = 8x
8x+5x = 13x 5.6a-3.6a = 2a 9a+0.03a = 9.03a
a+a = 2a 0.27t+2.33t = 2.6t 3.6b+4.4b = 8b
4a+6a = 10a 2a+4a = 6a 3.4x+2.6x = 6x
b-0.5b = 0.5b 5x+4x = 9x 4.8a+a = 5.8a
2a×2.5 = 5a 7x+3.4x = 10.4x 1.2x-x = 0.2x
7.5y-5y = 2.5y 15x-7x = 8x 8x-4x = 4x
9.2x+0.8x = 10x 8x-4x = 4x 15x-7.5x = 7.5x
数奥同步学答案
如果一个数与它自己相加、相减、相除其和、差、商相加的和为8.6,那么它是 3.8 。
( 8.6-1-0 ) ÷ 2 = 3.8
练35 四、简易方程
把方程圈出来
x+3 = 6 8x < 5 5x = 0
5-x < 5 9x > 8 8x+8 < 17
3.2x-x = 1.6 2y+3y = 152 85 > 2x
4.8+3.9 = 8.7 5500÷500 = 11 506-109+3 = 400
0×320 = 0 5.4-2.3 = 3.1 3400-2000÷2 = 2400
720÷18 = 40 3.6÷3.6 = 1 13÷5÷1.3 = 2
31÷0.1 = 310 1.1×54 = 59.4 700-238-262 = 200
7.6×9.9 = 75.24 409+324 = 733 640÷16×5 = 200
0÷420 = 0 430÷10 = 43 420×2÷70 = 12
44×2.5 = 110 5.77-3.66 = 2.11 40.5-13.5+20.5 = 47.5
4.21+5.59 = 9.8 960+105 = 1065 16×4÷8 = 8
28×1.1 = 30.8 430÷0.01 = 43000 324×11÷11 = 324
420÷20 = 21 4.8+3.2 = 8 8.7+6.9+4.4 = 20
240-80 = 160 3.6÷0.1 = 36 750÷5÷30 = 5
3600÷180 = 20 1200÷300 = 4 31.9+21.1-10 = 43
6300÷90 = 70 45÷900 = 0.05 520÷13÷8 = 5
28×11 = 308 2.48-0.08 = 2.4 1400÷700×5 = 10
数奥同步学答案
某数减去8再乘以4最后加上7,得11,那么这个数先加上7再乘以4最后减去8,得 56 。
( 11 - 7 ) ÷ 4 + 8 = 9
( 9 + 7 ) × 4 - 8 = 56
练36 四、简易方程
480÷6 = 80 700÷20 = 35 0.32×0.5 = 0.16
5.6÷70 = 0.08 300×0.03 = 9 5.5÷5×80 = 88
87×9.9 = 861.3 4500÷500 = 9 400+4000-800 = 3600
400-173 = 227 550÷1.1 = 500 4.48÷4.48×0.1 = 0.1
45÷0.1 = 450 1.9×30 = 57 4.8÷48÷0.01 = 10
9.2-4.8 = 4.4 5400÷600 = 9 400÷50÷80 = 0.1
640÷40 = 16 3.6×101 = 363.6 24.3+17.7-12 = 30
360÷40 = 9 3.6×4-4.8 = 9.6 3.2÷0.01÷40 = 8
420÷21 = 20 0.54×3 = 1.62 4×0.25÷0.5 = 2
1.1×36 = 39.6 24×50 = 1200 5.94-3.48-1.52 = 0.94
570÷30 = 19 42×1.1 = 46.2 3.2×100÷80 = 4
320÷3.2 = 10 349-198 = 151 80×200÷400 = 40
24-12.5 = 11.5 13.4-11.6 = 1.8 7×0.9÷0.7 = 9
0÷4.8 = 0 0÷400 = 0 3.25×0÷25 = 0
1.38+22.2 = 23.58 3.11×6 = 18.66 400+560-298 = 662
箱子里装有同样数目的乒乓球和羽毛球,每次取出5个乒乓球和3个羽毛球,取了若干次后,乒乓球没有了,羽毛球还剩6个。问一共取了几次(列方程解)
解:设乒乓球总数为a,取球次数为b。则 a=5b a=3b+6
5b=a=3b+6 5b=3b+6 2b=6 b=3
答:一共取了3次。
数奥同步学答案
有面额5元和10元的人民币共43张,合计340元,那么5元币 18 张,10元币 25 张。
解:设5元币有f张,10元币有t张,则 f+t=43 5f+10t=340
10f+10t=430
10f-5f=430-340
5f=90
f=18 t=43-18=25
练37 四、简易方程
解方程:
x÷8 = 125 6x÷5 = 12 x÷0.05 = 60
解x = 125×8 解 6x = 60 解x = 60×0.05
x = 1000 x = 10 x = 3
x÷0.8 = 10 0.05x = 3.5 x-3.8 = 6.2
解x = 10×0.8 解 x = 3.5÷0.05 解 x = 6.2+3.8
x = 8 x = 70 x = 10
3x = 42 x-4.8 = 5.2 43-x = 38
解x = 42÷3 解 x = 5.2+4.8 解 x = 43-38
x = 14 x = 10 x = 5
40÷x = 8 x+4.2 = 7.8 27.2÷x = 6.8
解x = 40÷8 解 x = 7.8-4.2 解 x = 27.2÷6.8
x = 5 x = 3.6 x = 4
50×x = 350 2.3x = 6.9 2.5x = 60
解x = 350÷50 解 x = 6.9÷2.3 解 x = 60÷2.5
x = 7 x = 3 x = 24
450÷x = 90 3.5÷x = 0.7 x+15 = 41
解x = 450÷90 解 x = 3.5÷0.7 解 x = 41-15
x = 5 x = 5 x = 26
使方程左右两边相等的未知数的值,叫做方程的解。
数奥同步学答案
登山比赛中,小明上山时平均每分钟走40米,18分钟到达山顶。然后原路返回,平均每分钟走60米。小明上山时平均每分钟走 48 米。
[ ( 40×18 ) × 2 ] ÷ [ 18 + ( 40×18 )÷ 60 ] = 48 (米/分)
练38 四、简易方程
解方程:
x÷4.5 = 1.2 0.9x = 2.7 x-21 = 14
解x = 1.2×4.5 解 x = 2.7÷0.9 解 x = 14+21
x = 5.4 x = 3 x = 35
6.98-x = 6.7 0.8÷x = 10 47+x = 47
解x = 6.98-6.7 解 x = 0.8÷10 解 x = 47-47
x = 0.28 x = 0.08 x = 0
2.5x = 7.5 x-45 = 1000 6x = 42
解x = 7.5÷2.5 解 x = 1000+45 解 x = 42÷7
x = 3 x = 1045 x = 6
x+0.8 = 1.2 3x = 45 x÷7 = 12
解x = 1.2-0.8 解 x = 45÷3 解 x = 12×7
x = 0.4 x = 15 x = 84
x+21.5 = 34 1.6x = 3.36 24 x = 96
解 x = 34-21.5 解 x = 3.36÷1.6 解 x = 96÷24
x = 12.5 x = 2.1 x = 4
x-0.32 = 8.6 x+20 = 35 x-19 = 2
解x = 8.6+0.32 解 x = 35-20 解 x = 2+19
x = 8.92 x = 15 x = 21
求方程的解的过程,叫做解方程。
数奥同步学答案
甲、乙两城相距350千米,一艘客轮在其间往返航行,从甲城到乙城是顺流,用去10小时;从乙城返回甲城是逆流,用去14小时。那么船在静水中的时速是 30千米,水流时速是5千米。
解:设船在静水中的时速是c,水流时速是s
则 (c+s)×10 = (c-s)×14 = 350
10c+10s = 14c-14s
4c = 24s
c = 6s
(c+s)×10 = 350
(6s+s)×10 = 350
7s×10 = 350
s = 350÷70 = 5
c = 6s = 6×5 = 30
练39 四、简易方程
解方程:(以下由于“解”不好打印出来所以省略,同学们做题一定要写“解”
5x+6 = 10 7x-26 = 2 5x-39 = 56
解5x = 10-6 7x = 2+26 解 5x = 56+39
x = 4÷5 x = 28÷7 x = 95÷5
x = 0.8 x = 4 x = 19
16+4x = 76 3x+4 = 40 3.2x+4.8x = 80
4x = 76-16 3x = 40-4 8x = 80
x = 60÷4 x = 36÷3 x = 80÷8
x = 15 x = 12 x = 10
1.2x+2.8x = 10.4 12x-9x = 4.2 10x-6x = 40
4x = 10.4 3x = 4.2 4x = 40
x = 10.4÷4 x = 4.2÷3 x = 40÷4
x = 2.6 x = 1.4 x = 10
4x-2.6 = 1.4 6x+3 = 9 3 x+8x = 55
4x = 1.4+2.6 6x = 9-3 11x = 55
x = 4÷4 x = 6÷6 x = 55÷11
x = 1 x = 1 x = 5
0.92-8x = 0.52 4x-2 = 10 4.2x-1.9x = 4.6
8x = 0.92-0.52 4x = 10+2 2.3x = 4.6
x = 0.4÷8 x = 12÷4 x = 4.6÷2.3
x = 0.05 x = 3 x = 2
4.5 x+2.5x = 1.19 18+15x = 21 8x-4×14 = 0
7x = 1.19 15x = 21-18 8x = 56
x = 1.19÷7 x = 3÷15 x = 56÷8
x = 0.17 x = 0.2 x = 7
数奥同步学答案
王老师买2千克橘子和3千克香蕉,共用5.7元。李老师买7千克橘子和3千克香蕉,共用11.7元。那么1千克橘子1.2元,1千克香蕉1.1元。
解:设1千克橘子j元,1千克香蕉x元
则 2j+3x = 5.7 7j+3x = 11.7
x = (5.7-2×1.2)÷3 5j = 6
x = 3.3÷3 j = 6÷5
x = 1.1 j = 1.2
练40 四、简易方程
解方程:
15x-7.5x = 22.5 1.2x-x = 6 y+3y = 36
7.5x = 22.5 0.2x = 6 4y = 36
x = 22.5÷7.5 x = 6÷0.2 y = 36÷4
x = 3 x = 30 y = 9
22.1x+27.9x = 200 3.4x+2.6x = 7.2 6x-3x = 4.8
50x = 200 6x = 7.2 3x = 4.8
x = 200÷50 x = 7.2÷6 x = 4.8÷3
x = 4 x = 1.2 x = 1.6
9x-5x = 6.4 5x+7x = 42 3m+2m = 65
4x = 6.4 12x = 42 5m = 65
x = 6.4÷4 x = 42÷12 m = 65÷5
x = 1.6 x = 3.5 m = 13
3.5 x+6.5x = 1 4x-7.2 = 10 3 x+x = 180
10x = 1 4x = 10+7.2 4x = 180
x = 1÷10 x = 17.2÷4 x = 180÷4
x = 0.1 x = 4.3 x = 45
3.6x-1.2x = 4.8 0.8÷x = 10 5y+y = 96
2.4x = 4.8 10x = 0.8 6y = 96
x = 4.8÷2.4 x = 0.8÷10 y = 96÷6
x = 2 x = 0.08 y = 16
8x-4x = 20 x-45 = 1000 y+y = 33
4x = 20 x = 1000+45 2y = 33
x = 20÷4 x = 1045 y = 33÷2
x = 5 y = 16.5
数奥同步学答案
一列火车通过530米长的隧道要40秒,以同样的速度通过380米的大桥要用30秒钟,这列火车的速度是 15 米/秒,车长是 70 米。
解:设火车的速度是V米/秒,车长是L米
则 V = (530-380) ÷ (40-30) = 15
L = 40×15 - 530 = 70
练41 四、简易方程
解方程:
5x+8 = 10 11 x-4.5 = 17.5 21x-10x = 0.66
5x = 10-8 11x = 17.5+4.5 11x = 0.66
x = 2÷5 x = 22÷11 x = 0.66÷11
x = 0.4 x = 2 x = 0.06
x÷18 = 720 6.3+0.2x = 16.3 9x-6x = 4.8
x = 720×18 0.2x = 16.3-6.3 3x = 4.8
x = 12960 x = 10÷0.2 x = 4.8÷3
x = 50 x = 1.6
150+x = 420 8.6÷x = 17.2 0.8x+20 = 24
x = 420-150 17.2x = 8.6 0.8x = 24-20
x = 270 x = 8.6÷17.2 x = 4÷0.8
x = 0.5 x = 5
3.2+x = 4.8 x-4.9 = 15.8 13 x-10x = 0.96
x = 4.8-3.2 x = 15.8+4.9 3x = 0.96
x = 1.6 x = 20.7 x = 0.96÷3
x = 0.32
x-250 = 750 1.2x-x = 6 x+3x = 72
x = 750+250 0.2x = 6 4x = 72
x = 1000 x = 6÷0.2 x = 72÷4
x = 30 x = 18
x×8 = 1000 10 x-8x = 20 1.6+2.2x = 10.4
x = 1000÷8 2x = 20 2.2x = 10.4-1.6
x = 125 x = 20÷2 x = 8.8÷2.2
x = 10 x = 4
数奥同步学答案
甲乙两辆车同时从两地相对开出,甲车平均每小时行60千米,乙车平均每小时行55千米,相遇时,甲车比乙车多行45千米,则两地相距 1035 千米。
解: 45 ÷ (60-55) = 9 (小时)
9 × ( 60+55 ) = 1035 (千米)
练42 四、简易方程
解方程:
1.6x+2.4x = 10.4 435-x = 305 x-3 = 6
4x = 10.4 x = 435-305 x = 6+3
x = 10.4÷4 x = 130 x = 9
x = 2.6
8x-1.8 = 30.2 30.4+x = 40 9÷x = 1.5
8x = 30.2+1.8 x = 40-30.4 x = 9÷1.5
x = 32÷8 x = 9.6 x = 6
x = 4
x+2x = 66 0.07x = 3.5 8x-3x = 105
3x = 66 x = 3.5÷0.07 5x = 105
x = 66÷3 x = 50 x = 105÷5
x = 22 x = 21
56x-50x = 36 0.9x = 8.1 x-35 = 40
6x = 36 x = 8.1÷0.9 x = 40+35
x = 36÷6 x = 9 x = 75
x = 6
x+1.8 = 3.2 x+35 = 91 40-3x = 13
x = 3.2-1.8 x = 91-35 3x = 40-13
x = 1.4 x = 56 x = 27÷3
x = 9
x×30 = 69 x×3 = 57 6x-x = 125
x = 69÷30 x = 57÷3 5x = 125
x = 2.3 x = 19 x = 125÷5
x = 25
数奥同步学答案
甲乙两辆车同时从A、B两地相向而行,在距B地54千米处相遇。他们各自到达对方车站后立即返回原地,途中又在距A地42千米处相遇。两次相遇地点间的距离为 24 千米。
解:设A、B两城间距为S千米,两次相遇点间距为L
首次相遇时两车合起来走了A、B两城间距(S),其中乙车走了54千米;
再次相遇时两车合起来共走了S的三倍,那么乙车也应该走了54千米的三倍;但我们知道乙车实际走了A、B两城间距(S)加上折返的42千米。所以: 54×3 = S+42
S = 162-42
S = 120 (千米)
两次相遇点间距等于A、B两城间距减去相遇点到两头的距离,即:
L = S―54―42 = 120―54―42 = 24 (千米)
单元检测
2.5×0.04 = 0.1 0.42÷0.07 = 6 0.25×9×4 = 9
10-4.28 = 5.72 3.2×1.1 = 3.52 5.6×101-5.6 = 560
2.8÷0.7 = 4 2.8÷0.4 = 7 4.2÷0.7÷0.1 = 60
101×3.2 = 323.2 4.6×101 = 464.6 5.6÷0.8÷7 = 1
54÷60 = 0.9 27×9.9 = 267.3 1÷0.25×0.4 = 1.6
3.6×1.1 = 3.96 5.6÷0.8 = 7 0.3÷0.01÷10 = 3
0.36÷0.06 = 6 7.5÷2.5 = 3 4.8÷6÷0.8 = 1
0.84÷6 = 0.14 1.6×2.5 = 4 20×1.4×0.5 = 14
3.25×4 = 13 2.5×2.4 = 6 0.75÷0.5×6 = 9
2.125×8 = 17 1.25×16 = 20 0.6+0.4÷2 = 0.8
3.5÷0.07 = 50 1.25×24 = 30 2.6×9.9+2.6×0.1 = 26
4.8×0.5 = 2.4 12.5×32 = 400 0.5×4÷0.5×4 = 16
0.57÷0.19 = 3 1÷0.125 = 8 2.5×32×1.25 = 100
4.73÷4.3 = 1.1 10÷0.25 = 40 1.7×2.8+1.7×7.2 = 17
解方程:
x÷8 = 1.25 0.25x = 10 16÷x = 3.2
x = 1.25×8 x = 10÷0.25 3.2x = 16
x = 10 x = 40 x = 16÷3.2
x = 5
2.5x = 7.5 3.6x+6.4x = 1 12x-6.5x = 11
x = 7.5÷2.5 10x = 1 5.5x = 11
x = 3 x = 1÷10 x = 11÷5.5
x = 0.1 x = 2
算法技巧解析
P.50
自主训练
44÷0.5 1.32÷0.5 21÷0.25 132÷0.5
= 44×2 = 1.32×2 = 21×4 = 132×2
= 88 = 2.64 = 84 = 264
1.7÷0.2 3.21÷0.25 1.24÷0.125 0.4÷0.125
= 1.7×4 = 3.21×4 = 1.24×8 = 0.4×8
= 6.8 = 12.84 = 9.92 = 3.2
23÷0.5 50÷0.125 2.4÷0.25 3÷0.125
= 23×2 = 50×8 = 2.4×4 = 3×8
= 46 = 400 = 9.6 = 24
P.51
自主训练
1、
(4.8×7.5×8.1) ÷ (2.4×2.5×2.7)
= (4.8÷2.4) × (7.5÷2.5) × (8.1÷2.7)
= 2×3×3
= 18
2、
(3.2×2.8×6.4) ÷ (0.8×0.7×0.4)
= (3.2÷0.8) × (2.8÷0.7) × (6.4÷0.4)
= 4×4×16
= 256
3、
(10个0.625,11个8,以及12个2连乘)
(0.625×0.625×…×0.625)×(8×8×…×8)×(2×2×…×2)
= (0.625×8×2)10 × 8 × 2×2
= 1010×8×4
= 10000000000×32
= 320000000000