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【330502】第2章《一元一次不等式和一元一次不等式组》单元测试试卷及答案

时间:2025-02-09 11:35:22 作者: 字数:9393字

2章《一元一次不等式和一元一次不等式组》单元测试试卷及答案

(时间:90分钟,满分:100)

一、选择题(每小题4分,共32)

1.亮亮准备用自己节省的零花钱买一台英语复读机,他现在已存有45元,计划从现在起以后每个月节省30元,直到他至少有300元,设x个月后他至少有300元,则可以用于计算所需要的月数x的不等式是(  )

A30x45≥300 B30x45≥300

C30x45≤300 D30x45≤300

2.下列说法正确的是(  )

A5是不等式5x10的一个解

Bx5是不等式x50的解集

Cx≥5是不等式-x5的解集

Dx3是不等式x3≥0的解集

3.已知abc均为实数,若abc≠0.下列结论不一定正确的是(  )

Aacbc Bcacb

C <a href="/tags/1/" title="单元" class="c1" target="_blank">单元</a> <a href="/tags/4/" title="测试" class="c1" target="_blank">测试</a> <a href="/tags/46/" title="答案" class="c1" target="_blank">答案</a> <a href="/tags/54/" title="试卷" class="c1" target="_blank">试卷</a> <a href="/tags/165/" title="等式" class="c1" target="_blank">等式</a> <a href="/tags/844/" title="不等式" class="c1" target="_blank">不等式</a> Da2abb2

4.如图,有一条通过点(3,-2)的直线l.若四点(2a)(0b)(c,0)(d,-1)l上,则下列数值的判断,哪个正确?(  )

 <a href="/tags/1/" title="单元" class="c1" target="_blank">单元</a> <a href="/tags/4/" title="测试" class="c1" target="_blank">测试</a> <a href="/tags/46/" title="答案" class="c1" target="_blank">答案</a> <a href="/tags/54/" title="试卷" class="c1" target="_blank">试卷</a> <a href="/tags/165/" title="等式" class="c1" target="_blank">等式</a> <a href="/tags/844/" title="不等式" class="c1" target="_blank">不等式</a>

Aa3 Bb>-2 Cc<-3 Dd2

5.若不等式组 <a href="/tags/1/" title="单元" class="c1" target="_blank">单元</a> <a href="/tags/4/" title="测试" class="c1" target="_blank">测试</a> <a href="/tags/46/" title="答案" class="c1" target="_blank">答案</a> <a href="/tags/54/" title="试卷" class="c1" target="_blank">试卷</a> <a href="/tags/165/" title="等式" class="c1" target="_blank">等式</a> <a href="/tags/844/" title="不等式" class="c1" target="_blank">不等式</a> 有实数解,则实数m的取值范围是(  )

Am <a href="/tags/1/" title="单元" class="c1" target="_blank">单元</a> <a href="/tags/4/" title="测试" class="c1" target="_blank">测试</a> <a href="/tags/46/" title="答案" class="c1" target="_blank">答案</a> <a href="/tags/54/" title="试卷" class="c1" target="_blank">试卷</a> <a href="/tags/165/" title="等式" class="c1" target="_blank">等式</a> <a href="/tags/844/" title="不等式" class="c1" target="_blank">不等式</a> Bm <a href="/tags/1/" title="单元" class="c1" target="_blank">单元</a> <a href="/tags/4/" title="测试" class="c1" target="_blank">测试</a> <a href="/tags/46/" title="答案" class="c1" target="_blank">答案</a> <a href="/tags/54/" title="试卷" class="c1" target="_blank">试卷</a> <a href="/tags/165/" title="等式" class="c1" target="_blank">等式</a> <a href="/tags/844/" title="不等式" class="c1" target="_blank">不等式</a> Cm <a href="/tags/1/" title="单元" class="c1" target="_blank">单元</a> <a href="/tags/4/" title="测试" class="c1" target="_blank">测试</a> <a href="/tags/46/" title="答案" class="c1" target="_blank">答案</a> <a href="/tags/54/" title="试卷" class="c1" target="_blank">试卷</a> <a href="/tags/165/" title="等式" class="c1" target="_blank">等式</a> <a href="/tags/844/" title="不等式" class="c1" target="_blank">不等式</a> Dm <a href="/tags/1/" title="单元" class="c1" target="_blank">单元</a> <a href="/tags/4/" title="测试" class="c1" target="_blank">测试</a> <a href="/tags/46/" title="答案" class="c1" target="_blank">答案</a> <a href="/tags/54/" title="试卷" class="c1" target="_blank">试卷</a> <a href="/tags/165/" title="等式" class="c1" target="_blank">等式</a> <a href="/tags/844/" title="不等式" class="c1" target="_blank">不等式</a>

6.设“●”、“▲”、“■”表示三种不同的物体,现用天平称了两次,情况如图所示,那么这三种物体按质量从大到小的顺序排列应为(  )

 <a href="/tags/1/" title="单元" class="c1" target="_blank">单元</a> <a href="/tags/4/" title="测试" class="c1" target="_blank">测试</a> <a href="/tags/46/" title="答案" class="c1" target="_blank">答案</a> <a href="/tags/54/" title="试卷" class="c1" target="_blank">试卷</a> <a href="/tags/165/" title="等式" class="c1" target="_blank">等式</a> <a href="/tags/844/" title="不等式" class="c1" target="_blank">不等式</a>

 <a href="/tags/1/" title="单元" class="c1" target="_blank">单元</a> <a href="/tags/4/" title="测试" class="c1" target="_blank">测试</a> <a href="/tags/46/" title="答案" class="c1" target="_blank">答案</a> <a href="/tags/54/" title="试卷" class="c1" target="_blank">试卷</a> <a href="/tags/165/" title="等式" class="c1" target="_blank">等式</a> <a href="/tags/844/" title="不等式" class="c1" target="_blank">不等式</a>

7.已知关于x的不等式组 <a href="/tags/1/" title="单元" class="c1" target="_blank">单元</a> <a href="/tags/4/" title="测试" class="c1" target="_blank">测试</a> <a href="/tags/46/" title="答案" class="c1" target="_blank">答案</a> <a href="/tags/54/" title="试卷" class="c1" target="_blank">试卷</a> <a href="/tags/165/" title="等式" class="c1" target="_blank">等式</a> <a href="/tags/844/" title="不等式" class="c1" target="_blank">不等式</a> 的解集为3≤x5,则ab的值为(  )

Aa=-3b6 Ba6b=-3

Ca1b2 Da0b3

8.如图是测量一物体体积的过程:

步骤一:将180 mL的水装进一个容量为300 mL的杯子中;

步骤二:将三个相同的玻璃球放入水中,结果水没有满;

步骤三:再将一个同样的玻璃球放入水中,结果水满溢出.

 <a href="/tags/1/" title="单元" class="c1" target="_blank">单元</a> <a href="/tags/4/" title="测试" class="c1" target="_blank">测试</a> <a href="/tags/46/" title="答案" class="c1" target="_blank">答案</a> <a href="/tags/54/" title="试卷" class="c1" target="_blank">试卷</a> <a href="/tags/165/" title="等式" class="c1" target="_blank">等式</a> <a href="/tags/844/" title="不等式" class="c1" target="_blank">不等式</a>

根据以上过程,推测一个玻璃球的体积在下列哪一范围内?(1 mL1 cm3)(  )

A10 cm3以上,20 cm3以下 B20 cm3以上,30 cm3以下

C30 cm3以上,40 cm3以下 D40 cm3以上,50 cm3以下

二、填空题(每小题4分,共20)

9.一罐饮料净重500克,罐上注有“蛋白质含量≥0.4%”,则这罐饮料中蛋白质的含量至少为__________克.

10.若关于xy的二元一次方程组 <a href="/tags/1/" title="单元" class="c1" target="_blank">单元</a> <a href="/tags/4/" title="测试" class="c1" target="_blank">测试</a> <a href="/tags/46/" title="答案" class="c1" target="_blank">答案</a> <a href="/tags/54/" title="试卷" class="c1" target="_blank">试卷</a> <a href="/tags/165/" title="等式" class="c1" target="_blank">等式</a> <a href="/tags/844/" title="不等式" class="c1" target="_blank">不等式</a> 的解满足xy2,则a的取值范围为__________来源:http://www.bcjy123.com/tiku/

11.如图,直线ykxb经过A(2,1)B(1,-2)两点,则不等式 <a href="/tags/1/" title="单元" class="c1" target="_blank">单元</a> <a href="/tags/4/" title="测试" class="c1" target="_blank">测试</a> <a href="/tags/46/" title="答案" class="c1" target="_blank">答案</a> <a href="/tags/54/" title="试卷" class="c1" target="_blank">试卷</a> <a href="/tags/165/" title="等式" class="c1" target="_blank">等式</a> <a href="/tags/844/" title="不等式" class="c1" target="_blank">不等式</a>kxb>-2的解集为__________

 <a href="/tags/1/" title="单元" class="c1" target="_blank">单元</a> <a href="/tags/4/" title="测试" class="c1" target="_blank">测试</a> <a href="/tags/46/" title="答案" class="c1" target="_blank">答案</a> <a href="/tags/54/" title="试卷" class="c1" target="_blank">试卷</a> <a href="/tags/165/" title="等式" class="c1" target="_blank">等式</a> <a href="/tags/844/" title="不等式" class="c1" target="_blank">不等式</a>

12.如下图程序,要使输出值y大于100,则输入的最小正整数x__________

 <a href="/tags/1/" title="单元" class="c1" target="_blank">单元</a> <a href="/tags/4/" title="测试" class="c1" target="_blank">测试</a> <a href="/tags/46/" title="答案" class="c1" target="_blank">答案</a> <a href="/tags/54/" title="试卷" class="c1" target="_blank">试卷</a> <a href="/tags/165/" title="等式" class="c1" target="_blank">等式</a> <a href="/tags/844/" title="不等式" class="c1" target="_blank">不等式</a>

13.国际互联网编号分配机构IANA宣布,截至2011118日,可供分配的IPv4地址仅剩下3 551万个,预计到2011210IANAIPv4地址池中将不再有IPv4地址块.其中日期与剩余IP数对应的数量关系如下表:

时间x

1(118)

2

3

4

剩余IPy(万个)

3 551

3 396

3 241

3 086

201123日剩余IP地址数是__________万个,从2__________日开始,剩余IP地址数少于800万个.

三、解答题(48)

14(12)解下列不等式()

(1)解不等式 <a href="/tags/1/" title="单元" class="c1" target="_blank">单元</a> <a href="/tags/4/" title="测试" class="c1" target="_blank">测试</a> <a href="/tags/46/" title="答案" class="c1" target="_blank">答案</a> <a href="/tags/54/" title="试卷" class="c1" target="_blank">试卷</a> <a href="/tags/165/" title="等式" class="c1" target="_blank">等式</a> <a href="/tags/844/" title="不等式" class="c1" target="_blank">不等式</a>5x

(2)解不等式组: <a href="/tags/1/" title="单元" class="c1" target="_blank">单元</a> <a href="/tags/4/" title="测试" class="c1" target="_blank">测试</a> <a href="/tags/46/" title="答案" class="c1" target="_blank">答案</a> <a href="/tags/54/" title="试卷" class="c1" target="_blank">试卷</a> <a href="/tags/165/" title="等式" class="c1" target="_blank">等式</a> <a href="/tags/844/" title="不等式" class="c1" target="_blank">不等式</a> 并把它的解集在数轴上表示出来.

 <a href="/tags/1/" title="单元" class="c1" target="_blank">单元</a> <a href="/tags/4/" title="测试" class="c1" target="_blank">测试</a> <a href="/tags/46/" title="答案" class="c1" target="_blank">答案</a> <a href="/tags/54/" title="试卷" class="c1" target="_blank">试卷</a> <a href="/tags/165/" title="等式" class="c1" target="_blank">等式</a> <a href="/tags/844/" title="不等式" class="c1" target="_blank">不等式</a>

15(8)是否存在整数m,使不等式mxm3x2的解集为x<-4?如果存在,请求出m的值;如果不存在,请说明理由.

16.(14)福岛核爆炸后,日本南方某蔬菜培育中心决定向灾区配送无辐射蔬菜和水果共3 200箱,其中水果比蔬菜多800箱.

(1)求水果和蔬菜各有多少箱?

(2)现计划租用甲、乙两种货车共8辆,一次性将这批水果和蔬菜全部运往该乡中小学.已知每辆甲种货车最多可装水果400箱和蔬菜100箱,每辆乙种货车最多可装水果和蔬菜各200箱,则运输部门安排甲、乙两种货车时有几种方案?请你帮助设计出来;

(3)(2)的条件下,如果甲种货车每辆需付运费4 000元,乙种货车每辆需付运费3 600元.运输部门应选择哪种方案可使运费最少?最少运费是多少元?

17(14)节约1度电,可以减少0.785千克碳排放.某省从201161日起执行新的居民生活用电价格,一户一表居民用户将实施阶梯式累进电价:月用电量低于50千瓦时(50千瓦时)部分不调整,电价每千瓦时0.53元;月用电量在51200千瓦时部分,电价每千瓦时上调0.03元;月用电量超过200千瓦时部分,电价每千瓦时上调0.10元.

小明家属一户一表居民用户,将实施阶梯式累进电价.7月份至8月份的电费缴款情况如下表:

计算日期

上期示度

本期示度

电量

金额()

20110710

3 230

3 296

66

34.98

20110810

3 296

3 535

239

135.07

(1)根据上述资料对阶梯式累进电价的描述,设电量为x千瓦时,金额为y元,表示出金额对于电量的函数关系,并画出图象.来源:http://www.bcjy123.com/tiku/

(2)解释小明家8月份电费的计算详情.

(3)为节约用电,小明对以后制订了详细的用电计划,如果实际每天比计划多用2千瓦时,下月用电量将会超过240千瓦时;如果实际每天比计划节约2千瓦时,那么下月用电量将会不超过180千瓦时,下月(30)每天用电量应控制在什么范围内?

参考答案

1答案:B

2答案:C

3答案:D

4答案:C

5解析:化简不等式组,得 <a href="/tags/1/" title="单元" class="c1" target="_blank">单元</a> <a href="/tags/4/" title="测试" class="c1" target="_blank">测试</a> <a href="/tags/46/" title="答案" class="c1" target="_blank">答案</a> <a href="/tags/54/" title="试卷" class="c1" target="_blank">试卷</a> <a href="/tags/165/" title="等式" class="c1" target="_blank">等式</a> <a href="/tags/844/" title="不等式" class="c1" target="_blank">不等式</a> 因为它有解,所以m <a href="/tags/1/" title="单元" class="c1" target="_blank">单元</a> <a href="/tags/4/" title="测试" class="c1" target="_blank">测试</a> <a href="/tags/46/" title="答案" class="c1" target="_blank">答案</a> <a href="/tags/54/" title="试卷" class="c1" target="_blank">试卷</a> <a href="/tags/165/" title="等式" class="c1" target="_blank">等式</a> <a href="/tags/844/" title="不等式" class="c1" target="_blank">不等式</a> .

答案:A

6解析:由题意,知“●●”=“▲”,“■”>“▲”,由此可以判断它们的大小.

答案:B

7解析:化简不等式组,得 <a href="/tags/1/" title="单元" class="c1" target="_blank">单元</a> <a href="/tags/4/" title="测试" class="c1" target="_blank">测试</a> <a href="/tags/46/" title="答案" class="c1" target="_blank">答案</a> <a href="/tags/54/" title="试卷" class="c1" target="_blank">试卷</a> <a href="/tags/165/" title="等式" class="c1" target="_blank">等式</a> <a href="/tags/844/" title="不等式" class="c1" target="_blank">不等式</a> 因为其解集为3≤x5,故得方程组 <a href="/tags/1/" title="单元" class="c1" target="_blank">单元</a> <a href="/tags/4/" title="测试" class="c1" target="_blank">测试</a> <a href="/tags/46/" title="答案" class="c1" target="_blank">答案</a> <a href="/tags/54/" title="试卷" class="c1" target="_blank">试卷</a> <a href="/tags/165/" title="等式" class="c1" target="_blank">等式</a> <a href="/tags/844/" title="不等式" class="c1" target="_blank">不等式</a> 解得a=-3b6.

答案:A

8解析:以上过程是根据物理学知识用杯子来估测玻璃球的体积范围,不妨设一个玻璃球的体积为x cm3,根据题意,得 <a href="/tags/1/" title="单元" class="c1" target="_blank">单元</a> <a href="/tags/4/" title="测试" class="c1" target="_blank">测试</a> <a href="/tags/46/" title="答案" class="c1" target="_blank">答案</a> <a href="/tags/54/" title="试卷" class="c1" target="_blank">试卷</a> <a href="/tags/165/" title="等式" class="c1" target="_blank">等式</a> <a href="/tags/844/" title="不等式" class="c1" target="_blank">不等式</a>x <a href="/tags/1/" title="单元" class="c1" target="_blank">单元</a> <a href="/tags/4/" title="测试" class="c1" target="_blank">测试</a> <a href="/tags/46/" title="答案" class="c1" target="_blank">答案</a> <a href="/tags/54/" title="试卷" class="c1" target="_blank">试卷</a> <a href="/tags/165/" title="等式" class="c1" target="_blank">等式</a> <a href="/tags/844/" title="不等式" class="c1" target="_blank">不等式</a> ,即30x40,应选C.

答案:C

9答案:2 来源:http://www.bcjy123.com/tiku/

10解析:解关于xy的二元一次方程组 <a href="/tags/1/" title="单元" class="c1" target="_blank">单元</a> <a href="/tags/4/" title="测试" class="c1" target="_blank">测试</a> <a href="/tags/46/" title="答案" class="c1" target="_blank">答案</a> <a href="/tags/54/" title="试卷" class="c1" target="_blank">试卷</a> <a href="/tags/165/" title="等式" class="c1" target="_blank">等式</a> <a href="/tags/844/" title="不等式" class="c1" target="_blank">不等式</a>x <a href="/tags/1/" title="单元" class="c1" target="_blank">单元</a> <a href="/tags/4/" title="测试" class="c1" target="_blank">测试</a> <a href="/tags/46/" title="答案" class="c1" target="_blank">答案</a> <a href="/tags/54/" title="试卷" class="c1" target="_blank">试卷</a> <a href="/tags/165/" title="等式" class="c1" target="_blank">等式</a> <a href="/tags/844/" title="不等式" class="c1" target="_blank">不等式</a>y <a href="/tags/1/" title="单元" class="c1" target="_blank">单元</a> <a href="/tags/4/" title="测试" class="c1" target="_blank">测试</a> <a href="/tags/46/" title="答案" class="c1" target="_blank">答案</a> <a href="/tags/54/" title="试卷" class="c1" target="_blank">试卷</a> <a href="/tags/165/" title="等式" class="c1" target="_blank">等式</a> <a href="/tags/844/" title="不等式" class="c1" target="_blank">不等式</a> .因为xy2,所以 <a href="/tags/1/" title="单元" class="c1" target="_blank">单元</a> <a href="/tags/4/" title="测试" class="c1" target="_blank">测试</a> <a href="/tags/46/" title="答案" class="c1" target="_blank">答案</a> <a href="/tags/54/" title="试卷" class="c1" target="_blank">试卷</a> <a href="/tags/165/" title="等式" class="c1" target="_blank">等式</a> <a href="/tags/844/" title="不等式" class="c1" target="_blank">不等式</a>2,解得a4.

答案:a4

11答案:1x2

12答案:186

13解析:观察表格发现,每增加一天,剩余IP地址数将少155万个,因此剩余IP地址数与时间是一次函数关系,设ykxb(kb是常数,且k≠0),则

 <a href="/tags/1/" title="单元" class="c1" target="_blank">单元</a> <a href="/tags/4/" title="测试" class="c1" target="_blank">测试</a> <a href="/tags/46/" title="答案" class="c1" target="_blank">答案</a> <a href="/tags/54/" title="试卷" class="c1" target="_blank">试卷</a> <a href="/tags/165/" title="等式" class="c1" target="_blank">等式</a> <a href="/tags/844/" title="不等式" class="c1" target="_blank">不等式</a>

所以y=-155x3 706.

23日是第17天,故当x17时,y=-155×173 7061 071.所以,201123日剩余IP地址数为1 071万个.

y800,即-155x3 706800,解得x <a href="/tags/1/" title="单元" class="c1" target="_blank">单元</a> <a href="/tags/4/" title="测试" class="c1" target="_blank">测试</a> <a href="/tags/46/" title="答案" class="c1" target="_blank">答案</a> <a href="/tags/54/" title="试卷" class="c1" target="_blank">试卷</a> <a href="/tags/165/" title="等式" class="c1" target="_blank">等式</a> <a href="/tags/844/" title="不等式" class="c1" target="_blank">不等式</a> .所以从第19日,即25日开始,剩余IP地址数少于800万个.

答案:1 071 5

14解:(1)去分母,得x1≤3(5x)

去括号,得x1≤153x.

移项,合并同类项,得4x≤16.

系数化为1,得x≤4.

这个不等式的解集在数轴上表示如图所示.

 <a href="/tags/1/" title="单元" class="c1" target="_blank">单元</a> <a href="/tags/4/" title="测试" class="c1" target="_blank">测试</a> <a href="/tags/46/" title="答案" class="c1" target="_blank">答案</a> <a href="/tags/54/" title="试卷" class="c1" target="_blank">试卷</a> <a href="/tags/165/" title="等式" class="c1" target="_blank">等式</a> <a href="/tags/844/" title="不等式" class="c1" target="_blank">不等式</a>

(2)解不等式①,得x>-2

解不等式②,得x≤1.

所以不等式组的解集是-2x≤1.

这个解集在数轴上表示如图所示.

 <a href="/tags/1/" title="单元" class="c1" target="_blank">单元</a> <a href="/tags/4/" title="测试" class="c1" target="_blank">测试</a> <a href="/tags/46/" title="答案" class="c1" target="_blank">答案</a> <a href="/tags/54/" title="试卷" class="c1" target="_blank">试卷</a> <a href="/tags/165/" title="等式" class="c1" target="_blank">等式</a> <a href="/tags/844/" title="不等式" class="c1" target="_blank">不等式</a>

15解:假设存在符合条件的整数m,将原不等式整理,得(m3)xm2.m30,即m3时,有x.根据题意,得=-4,解得m2.因此,存在符合条件的整数m,且当m2时,使不等式的解集为x<-4.

16. 解:(1)设水果有x箱,则蔬菜有(x800)箱.

x(x800)3 200,解这个方程,得x2 000.

所以x8001 200.

所以水果和蔬菜分别为2 000箱和1 200箱.

(2)设租用甲种货车a辆,则租用乙种货车(8a)辆.根据题意,得

 <a href="/tags/1/" title="单元" class="c1" target="_blank">单元</a> <a href="/tags/4/" title="测试" class="c1" target="_blank">测试</a> <a href="/tags/46/" title="答案" class="c1" target="_blank">答案</a> <a href="/tags/54/" title="试卷" class="c1" target="_blank">试卷</a> <a href="/tags/165/" title="等式" class="c1" target="_blank">等式</a> <a href="/tags/844/" title="不等式" class="c1" target="_blank">不等式</a>

解这个不等式组,得2≤a≤4.

因为a为整数,所以a234,安排甲、乙两种货车时有3种方案.

设计方案分别为:

甲车2辆,乙车6辆;②甲车3辆,乙车5辆;③甲车4辆,乙车4辆;

(3)3种方案的运费分别为:

2×4 0006×3 60029 600元;

3×4 0005×3 60030 000元;

4×4 0004×3 60030 400元.

故方案①的运费最少,最少运费是29 600元.

所以,运输部门应选择甲车2辆,乙车6辆,可使运费最少,最少运费是29 600元.

17解:(1)阶梯式累进电价的数学模型可用分段函数表示,设电量为x千瓦时,金额为y元,则有y

y <a href="/tags/1/" title="单元" class="c1" target="_blank">单元</a> <a href="/tags/4/" title="测试" class="c1" target="_blank">测试</a> <a href="/tags/46/" title="答案" class="c1" target="_blank">答案</a> <a href="/tags/54/" title="试卷" class="c1" target="_blank">试卷</a> <a href="/tags/165/" title="等式" class="c1" target="_blank">等式</a> <a href="/tags/844/" title="不等式" class="c1" target="_blank">不等式</a>

函数图象如下图所示:

 <a href="/tags/1/" title="单元" class="c1" target="_blank">单元</a> <a href="/tags/4/" title="测试" class="c1" target="_blank">测试</a> <a href="/tags/46/" title="答案" class="c1" target="_blank">答案</a> <a href="/tags/54/" title="试卷" class="c1" target="_blank">试卷</a> <a href="/tags/165/" title="等式" class="c1" target="_blank">等式</a> <a href="/tags/844/" title="不等式" class="c1" target="_blank">不等式</a>

(2)基本部分:239×0.53126.67()

调价部分:

50200千瓦时之间调价部分:(20050)×0.034.5()

超过200千瓦时的调价部分:(239200)×0.103.9()

合计调价部分电费:4.53.98.4()

合计电费:126.678.4135.07()

(3)设下月每天用电量为x,根据题意列不等式组,得

 <a href="/tags/1/" title="单元" class="c1" target="_blank">单元</a> <a href="/tags/4/" title="测试" class="c1" target="_blank">测试</a> <a href="/tags/46/" title="答案" class="c1" target="_blank">答案</a> <a href="/tags/54/" title="试卷" class="c1" target="_blank">试卷</a> <a href="/tags/165/" title="等式" class="c1" target="_blank">等式</a> <a href="/tags/844/" title="不等式" class="c1" target="_blank">不等式</a> 解之,得6x≤8.

所以下月每天用电量应控制在大于6千瓦时小于或等于8千瓦时范围内.