当前位置:首页 > 八年级 > 数学试卷

【330606】第二章 一元一次不等式与一元一次不等式组 周周测2(2.2)

时间:2025-02-11 18:29:21 作者: 字数:7471字

一、选择题

1.ab,则下列不等式成立的是       

A. acbc                             <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> B. ac2bc2                             <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> C.  <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/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> D. a+cb+c

2.如果ab,那么下列各式中错误的是(    )  

A. a+5>b+5                              <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> B. 5a>5b                              <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> C.  <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/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> D. 5a>-5b

3.已知ab,则下列不等式不一定正确的是(   

A. 2a-32b-3                         <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> B. 2-a2-b                         <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> C. 3a-3b+10                         <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> D. a2b2

4.已知xy,下列不等式一定成立的是(  )

A. x+1y+1                         <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> B. 2x2y                         <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> C. 2x+12y+1                         <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> D. 2x2y

5.已知实数ab,若ab,则下列结论正确的是(  

A. a2b2                         <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> B. 2+a2+b                         <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> C.  <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/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/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> D. 2a<﹣2b

6.如果mn0,那么下列结论中错误的是(    

A. m9n9                            <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> B. m>-n                            <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> C.  <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/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> D.  <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.mn,下列不等式不一定成立的是(  

A. m+2n+2                            <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> B. 2m2n                            <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> C.  <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/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/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> D. m2n2

8.ab,则下列各式中正确的是(  

A. 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> b  <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>                    B. 4a>﹣4b                   C. 2a+1<﹣2b+1                   D. a2b2

二、填空题

9.如果ab.那么32a ________32b.(用不等号连接)

10.ab,则﹣2a+5________2b+5(用填空.)

11.不等式两边乘(或除以)同一个________,不等号的方向改变,即如果a>b,c<0,那么ac < bc.(  <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/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.比较大小:﹣a ________2a(填=”“”“

13.不等号填空:若ab0,则﹣ <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/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/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/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> 2a1________ 2b1

14.ab,且c为实数,则ac2 ________bc2

15.a0,则﹣3a+2________ 0.(填”“=”“

16.ab,则﹣a________ b2a1________ 2b1

三、解答题

17.现有不等式的性质:
在不等式的两边都加上(或减去)同一个整式,不等号的方向不变;
在不等式的两边都乘以同一个数(或整式),乘的数(或整式)为正时不等号的方向不变,乘的数(或整式)为负时不等式的方向改变.
请解决以下两个问题:
1)利用性质①比较2aa的大小(a≠0);
2)利用性质②比较2aa的大小(a≠0).



18.阅读下列材料: 解答已知xy=2,且x1y0,试确定x+y的取值范围有如下解法:
xy=2x=y+2
x1y+21.即y>﹣1
y01y0…①
同理得:1x2 …②
由①+②得﹣1+1y+x0+2
x+y的取值范围是0x+y2
请按照上述方法,完成下列问题:已知xy=3,且x2y1,则x+y的取值范围.





19.将下列不等式化成xa”xa”的形式:

1x17<﹣5

2 <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> >﹣3










答案:

1.D 2.D 3.D 4.B 5.D 6.C 7.D 8.C 9.> 10.< 11. <

12.< 13.> > < 14. 15.> 16.> <

17. 解:(1a0时,a+aa+0,即2aa
a
0时,a+aa+0,即2aa
2a0时,21,得2a1a,即2aa
a
0时,21,得2•a1•a,即2aa


  1. 解:(1)∵x-y=3
    ∴x=y+3
    ∵x2
    ∴y+32
    ∴y-1
    又∵y1
    ∴-1y1…①
    同理可得2x4…②
    由①+②得:-1+2x+y1+4
    ∴x+y的取值范围是1x+y5
    故答案为:1x+y5


19.解:(1x12. 2x6.