山东省济南市槐荫区2020-2021学年八年级下学期期中考试数学试题答案

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八年级数学试题参考答案与评分标准
一、选择题
题号
1
2
3
4
5
6
7
8
9
10
11
12
答案
A
C
B
D
C
D
A
A
C
B
D
B
二、填空题
13. －5
14. x（x
－
2）
15. 2
16. 50
17.
32
18.
41
三、解答题
19.（1）解：原式=
 
43 2x
·································································· 1 分
=
  
223 xx
···························································· 3 分
（2）解：原式=
··············································· 4 分
=
 
2
32 nm
································································ 6 分
20.（1）解：原式=
xbx
ba
2
12 2
··························································· 1 分
2
2
x
a
········································································ 2 分
（2）解：
 
232 xx
······································································· 3 分
∴
6x
············································································· 4 分
检验，将
6x
带入原方程，得
左边
4
1
，右边
4
1
，
左边＝右边 ··········································································· 5 分
所以，
6x
为原方程的根 ························································ 6 分
21. 解：原式
1
)
11
12
(
a
a
a
a
a
a
························································ 1 分
=
11
12
a
a
a
aa
=
11
1
a
a
a
a
···································································· 3 分
=
1a
a
··········································································· 4 分
当a=2时，原式=
12
2
=2 ····································································· 6 分
22.解：（1）图形正确 ·········································································· 3 分
如图所示：△A1B1C1即为所求； ···················································· 4 分
（2）图形正确 ·········································································· 7 分
如图所示：△A1B2C2即为所求； ···················································· 8 分
第 2 页(共 6 页)
23.解：设该企业原计划每天生产 x万个口罩，则在实际生产时每天生产 1.5x万个口罩，
·································································································· 1 分
根据题意得：
2
5.1
120120
xx
································································ 5 分
40 2
x
························································································· 6 分
20x
·························································································· 7 分
经检验：x＝20 是原分式方程的解，且符合题意
答：该企业原计划每天生产 20 万个口罩．··········································· 8 分
24.解：（1）证明：∵AB∥CE，
∴∠CAD＝∠ACE，∠ADE＝∠CED． ················································ 1 分
∵F是AC 中点，
∴AF＝CF， ·················································································· 2 分
在△AFD 与△CFE 中，
CFAF
CEDADE
ACECAD
，
∴△AFD≌△CFE（AAS）， ······························································ 3 分
∴AD＝CE， ················································································· 4 分
∵AD∥CE，
∴四边形 ADCE 是平行四边形； ························································ 5 分
（2）解：过点 C作CG⊥AB 于点 G． ················································ 6 分
∵CD＝BD，∠B＝30°，
∴∠DCB＝∠B＝30°，
∴∠CDA＝60°． ············································································ 7 分
在△ACG 中，∠AGC＝90°，
6AC
，∠CAG＝45°，
∴
3AGCG
． ········································································· 8 分
在△CGD 中，∠DGC＝90°，∠CDG＝60°，
3CG
，
山东省济南市槐荫区2020-2021学年八年级下学期期中考试数学试题答案.pdf

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