浙江省杭州市富阳区富春中学2019-2020学年上学期9月月考七年级数学试卷(含答案)
浙江省杭州市富阳区富春中学2019-2020学年上学期9月月考七年级数学试卷
一、选择题:本大题有 10个小题,每小题 3分,共 30分.在每小题给出的四个选项中,只有一项是符合题目要求的.
1. 2090 的相反数是()
A.-2090 B.2090 C.±2090 D.2090
2. a b等于()
A.b 个 a 相加B.a 个 b 相加C.b 个 a 相乘D.a 个 b 相乘
3.-5+3+7-1=-5-1+3+7 是应用了()
A.加法交换律B.加法结合律
C.分配律D.加法交换律与结合律
4.在-3.15,-0.01,-1,-212 这些数中,最大的数是()
A.-1 B.-212 C.-0.01 D.-3.15
5.太阳与地球的距离约为 150 000 000 000 米,数据 150 000 000 000 用科学记数法表示为()A.15×1012 B.1.5×1011 C.0.15×1011 D.15×1010
6.有理数 a,b 在数轴上对应的位置如图所示,则()
A.a+b>0 B.a-b>0 C.b-a<0 D.b-a>0
7.若一个数减去-2 的差是-5,则这个数乘以-2 的积是()
A.-6 B.6 C.-14 D.14
8.已知 a,b 互为相反数,则下列选项一定正确的是()
A.5ab=0 B.5a+5b=0 C. 5 5 =0
9.已知|x|=2,y=9,则 x+y 的值为()
A.11 B.7 C.11 或 7 D.11 或-7
10.小明的学校、家和书店依次座落在一条东西走向的大街上,学校在家的西边 200 米,书店在家东边 1000 米,小明从家里出发沿着街边练习跑步,向东跑了 1000 米,接着又向西跑了 1200 米,此时小明的位置在()A.家B.学校C.书店D.不在上述地方
二、填空题:本大题有 6个小题,每小题 4分,共 24分.
11.大于-2.2 的负整数是
12.把数轴上的点 A 移动 3 个单位,恰好与表示-10 的点重合,则点 A 表示的数为
13.用四舍五入法将 566.5317 取近似数,要求精确到个位数,则 566.5317≈
14.计算-22×(-3)2的值是
(本题满分 6 分)三、解答题:本大题有 7个小题,共 66分.解答应写出文字说明、证明过程或演算步骤.17.
计算:
18.(本题满分 8 分)计算:
19.(本题满分 8 分)计算:
20.(本题满分 10 分)已知|a|=3,|b|=2,且 a
21.(本题满分 10 分)下表是潮汛期记录的某河一周内的水位变化情况(正号表示水位比前一天上升,负号表示水位比前一天下降,上周末的水位恰好达到警戒水位,单位:米)
(1
离分别是多少?
(2)与上周末相比,本周末河流的水位是上升还是下降了?
(本题满分 12 分)点 A,B 在数轴上分别表示有理数 a,b,A,B 两点间的距离表示为|AB|.且|AB|=|a-b|.
22.
(1)①数轴上表示 2 和 7 的两点之间的距离=;
②数轴上表示-3 和-6 的两点之间的距离=;
③数轴上表示 4 和-3 的两点之间的距离=
(2)点 A,B 分别表示 x 和 2.
①若|AB|=2,求 x 的值.
②另有一点 C 表示 4,且|x-4|+|x-2|取得最小值,则 x 的取值范围是,最小值是(直接写出答案)
参考答案及评分建议
一、选择题:本大题有 10 个小题,每小题 3 分,共 30 分.在每小题给出的四个选项中,只有一项是符合题
目要求的.
二、填空题:本大题有 6 个小题,每小题 4 分,共 24 分.
11.-2 和-1
12.-7 或-13 13.567
14.-36 15.-1
16.②③⑤ 三、解答题:本大题有 7 个小题,共 66 分.解答应写出文字说明、证明过程或演算步骤.
17.(本题满分 6 分)
解:(1)原式=1-7=-6; ·············································································3 分(2 原式=4+3×(-
8) +27 ···········································································1 分
=4-24+27 =7. ·························································································2 分 18.(本题满分 8 分)
解:(1)原式=30÷(- 301
) ············································································2 分
=30×(-30 ) ··············································································1 分
=-900; ···················································································1 分
(2)原式=-0.5+3
1
4 +2.75-7.5=-0.5-7.5+(3 1
4 +2.7
5 )
=-8+6= -2············································································4 分
19.(本题满分 8 分)
解:(1)原式=25×8-60=200-60=140; ··························································4 分(2)原式=16×4
-5=-59. ······································································4 分
20.(本题满分 10 分)
解:当 a =-3,b =2 时, ················································································3 分原式=-
1;··························································································2 分当a=-3,b=-2时,·············································································3分原式=-125.·······················································································2 分
21.(本题满分10 分)
解:(1)周五最高,周一最低,都在警戒水位之上,距离分别为1.07 米和0.2 米;
···································································································5 分
(2)∵+0.20+0.81-0.35+0.13+0.28-0.36-0.01=0.71 ·····································3 分∴本周末河流的水
位上升了.····························································2 分
22.(本题满分12 分)
解:(1)①5;②3;③7;·············································································6 分(2)①若|AB|=2,则|x-2|=2,所以x-2=±2,所以x=2±2,所以x的值为4 或0.
·······························································································3 分
②借助数轴分析,不难发现,x 在表示2与4的点之间,(包括表示2与4的点),
所以2≤x≤4,此时最小值是2.·······················································3 分
23.(本题满分12 分)
解:(1)x=1= 2,x =1= -1,x =1=1;································6 分
2131- 241- ( -1)2
1 -2
(2)由于这一组数呈现每三个数重复的规律,且2020=3×673+1,所以第2020 个数与第
1 个数相同,所以x2020的值为1 2;······················································3 分
(3)若第一个数记a,则
x =1
,x =
1
21- a31
1 -1 -a
= 1 -a=1 -a,x =1=- a=-a= a ;
- a -1-a 1 -a- a -1+ a-1
14
1 --a
所以这一组数呈现每三个数重复的规律,3001=3×1000+1,所以x3001的值为a.···································································································3 分