（浙江宁波11月份月考）2020-2021学年第一学期七年级数学练习题

这是一份（浙江宁波11月份月考）2020-2021学年第一学期七年级数学练习题，文件包含浙江宁波2020-2021学年第一学期七年级数学浙教版docx、浙江宁波2020-2021学年第一学期七年级数学浙教版参考答案及评分建议docx等2份试卷配套教学资源，其中试卷共7页， 欢迎下载使用。

一、选择题（每小题 3 分，共 30 分）
二、填空题（每小题 4 分，共 24 分）
11．±312．12
13．－414．  5
2
15．－4 039x2 02016．20
三、解答题（本大题有 8 小题，共 66 分）
17．（本题 6 分）
解：（1）原式 8  (18)  4
9
=－8－8
=－16．···················································································3 分
1
2
3
4
5
6
7
8
9
10
B
C
A
B
D
C
B
A
D
D
（2）原式
=
5  3  (
5
 3 
 2)
5
5  2
=－1． ····················································································3 分
18．（本题 6 分）
解：（1）移项，得 4x－2x=5+1，
19．（本题 6 分）
解：如图所示（答案不唯一）：
···················································4 分
·····················································6 分
20．（本题 8 分）
解：2A+B=2(－a2+2ab+2b2)+2a2－2ab－4b2
=－2a2+4ab+4b2+2a2－2ab－4b2
合并同类项，得 2x=6，
系数化为 1，得 x=3． ································
································
·······
3 分
（2）去分母，得 2(2x－5)+3(3－x)=12，
去括号，得 4x－10+9－3x=12，
移项、合并同类项，得 x=13．································
····························
3 分
=2ab， ·························································································5 分
当 a  2 ， b  3 时，原式=2ab= 2  ( 2)  3  2 ．8 分
3232
21．（本题 8 分）
解：（1）由题意，得 m+1=3 且 3－n=0，
∵x=1，
∴x3+2x2+2 020
=1+2+2 020
=2 023．····················································································8 分
22．（本题 10 分）
解：（1）由题意，得 3a－4=2(1－2a)－3， ························································3 分
3a－4=2－4a－3，
3a+4a=2－3+4，
7a=3，
解得a  3 ．···················································································5 分
7
（2）当 1－2a 与 3a－4 互为相反数时，
1－2a+3a－4=0，解得 a=3， ······························································7 分
23．（本题 10 分）
解：（1）设小明 3 月份的存取金额为 x 元．
由题意，得 500+x+(－150)+600+(－250)=400，4 分
解得 x=－300， ···············································································6 分答：小明 3 月份取出 300 元．
（2）2 月累计：500 元；
3 月累计：500+(－300)=200（元），
4 月累计：200+(－150)=50（元），
5 月累计：50+600=650（元），
6 月累计：400 元，
所以小明储蓄卡上 5 月份的金额最多． ··············································10 分
24．（本题 12 分）
∴m=2，n=3， ································································
···············
2 分
∴mn+(m－n)2 021=23+(2－3)2 021=8－1=7． ································
············
4 分
（2）由（1）得，xm+1+2x2+3x－nx+2 020=x3+2x2+2 020． ·······························
6 分
此时 1－2a=1－2×3 =－5，3a－4=3×3 －4=5，
所以这个数是 52=25；
当 1－2a 与 3a－4 相等时，
1－2a=3a－4，解得 a=1， ································
································
9 分
此时 1－2a=1－2×1 =－1，3a－4=3×1 －4=－1，
所以这个数是(－1)2=1，
综上，这个数是 25 或 1．································
································
10 分
解：（1）17×3.4+(27 －17)×5.32 =111（元）． ·······················································4 分答：小明家 10 月份的水费是 111 元．
（2）17×3.4 =57.8（元），
17×3.4+ (31－17)×5.32 =132.28（元），
57.8<84.4<132.28，
∴小军家 10 月份的用水量在 17 立方米~31 立方米之间． 设小军家 10 月份的用水量为 x 立方米．
由题意，得 17×3.4+( x－17)×5.32 =84.4， ···············································6 分解得 x=22．····················································································8 分答：小军家 10 月份的用水量为 22 立方米．
（3）7×(x－31)+5.32×(31－17)+3.4×17 ·······················································10 分
=7x－84.72． ················································································12 分答：小红家 10 月份应缴的水费为(7x－84.72)元．