海南省文昌市2018-2019学年七年级上期末考试数学试题(解析? - 百度文库 ر

ʡIJ2018-2019ѧ꼶ĩѧ

һѡ⣨⹲14С⣬42.0֣ 1.

12018

෴( )

1

1

A. ?2018

𰸡A

B. 2018

C. ?2018 D. 2018

⣺2018෴?2018 ѡA

ֱ෴Ķó𰸣

Ҫ෴ȷ෴Ķǽؼ

2. 濴ͼеļ壬õƽͼȷ( )

11

A.

𰸡A

B. C. D.

⣺濴õͼΪ

ѡA

ݴ濴õͼͼɵô𰸣

⿼˼ͼ濴õͼͼ

3. 2?40?3ĸУС( )

A. ?6

𰸡D

B. ?2 C. 2 D. 6

1ҳ9ҳ

⣺2?40?3ĸУС2?(?4)=6 ѡD

Ƚ0֮ĹϵɣĴСұ߱ߴ ⿼0֮ĴСϵԵȸ0еĸ0С

4. ȷ( )

A. (?16)(?4)=?4 C. 4m?m=3

𰸡B

B. 2a2?3a2=?a2 D. x2y?xy2=0

⣺A(?16)(?4)=4 B2a2?3a2=?a2ȷ C4m?m=3m

Dx2yxy2ͬܺϲ ѡB

ϲͬ㼴ɣ

⿼ϲͬؼǸϲͬ㣮

5. ðٶؼʡʮŴ󡱣ٶΪҵؽԼ18 600 00018 600

000ÿѧʾΪ( )

A. 0.186108

𰸡B

B. 1.86107 C. 18.6106 D. 186105

⣺18600000=1.86107 ѡB

ݿѧıʾʽΪa10nʽ1|a|<10nΪ.ȷnֵʱҪԭaʱСƶ˶λnľֵСƶλͬ.ԭֵ>10ʱnԭľֵ<1ʱnǸ

⿼ѧıʾ.ѧıʾʽΪa10nʽ1|a|<10nΪʾʱؼҪȷȷaֵԼnֵ

6. 3a2+mb3(n?2)a4b3ͬǵĺΪ0mnֵ( )

A. ?2

𰸡A

B. ?1 C. 2 D. 1

⣺3a2+mb3(n?2)a4b3ͬ 2+m=4m=2 ǵĺΪ0

3a4b3+(n?2)a4b3=(n?2+3)a4b3=0n=?1 mn=?2 ѡA

ͬĸͬͬĸָҲͬɵmֵݺϲͬϵ

2ҳ9ҳ

ĸָ䣬ɵnֵټmnɵô𰸣

⿼ͬͬеͬͬĸָͬ׻㣬˳пij㣮

7. 121=2630䣬2ĶΪ( )

A. 15330

𰸡A

B. 16330 C. 17330 D. 18330

⣺ߡ1=2630䣬12 2=180?2630䣬=15330䣮 ѡA

ֱǻĶɣ

ҪǻĶ壬ȷջĶǽؼ

8. 2a=3b?4еʽвһ( )

3

A. 2a+4=3b

𰸡C

B. 2a?1=3b?5 C. 2am=3bm?4 D. a=2b?2

a=b?22a?1=3b?52am=⣺Ϊ2a=3b?42a+4=3b23bm?4m(m0) 2am=3bm?4 ѡC

ֱõʽĻжϵóɣ

Ҫ˵ʽĻʣ1ʽ߼ͬһ(ʽ)Եõʽ

2ʽ߳ͬһһΪԵõʽǽؼ

9. xһԪһη2x+a?4=0Ľx=2aֵ( )

3

A. ?8

𰸡D

B. 8 C. 2 D. 0

⣺x=2뷽̵ã4+a?4=0 ãa=0 ѡD

x=2뷽̼㼴aֵ

⿼һԪһη̵Ľ⣬̵Ľ⼴Ϊʹȵδֵ֪

10. ͼABCDĵһֱϣAB=CDиʽʾ߶AC

( )

A. AC=AD?CD B. AC=AB+BC C. AC=BD?AB D. AC=AD?AB

3ҳ9ҳ

𰸡C

⣺ABCDĵһֱϣAB=CD AC=AD?CD=AD?AB=AB+BC ѡC

߶εĺͲɵõۣ

⿼ľ롢߶εеĶԼ߶εĺͲ

11. ͼCD߶AB㣬CB=3cmDB=5cmD

ACе㣬߶ABijΪ( )

A. 7cm

𰸡A

B. 8cm C. 1lcm D. 13cm

⣺CB=3cmDB=5cm CD=5?3=2cm DACе㣬 AC=2CD=4cm

AB=AC+CB=4+3=7cm ѡA

ȸCB=3cmDB=5cmCDijٸDACеóACijɵóۣ

⿼ľ룬֪߶֮ĺ͡ϵǽĹؼ

12. ͼСսһǰڳͼ״DOC=120㣬

AOB=( )

A. 45

B. 70 C. 30 D. 60

𰸡D

⣺ߡDOB=AOC=90㣬DOC=120㣬 DOA=30㣬

ʡAOB=90?30=60㣮 ѡD

ֱûʽ֪ó𰸣

Ҫ˻ʣȷóDOA=30ǽؼ

13. ͼOCǡAOBƽߣODǡBOCƽߣ

AOD=81㣬AOBĶΪ( )

4ҳ9ҳ