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重庆西南师大附中 2009—2010 学年度上期期末考试
初三数学试题
(时间:120 分钟 满分:150 分)
一、选择题:(本大题 10 个小题,每小题 4 分,共 40 分)在每个小题的下面,都给出了代
号为 A、B、C、D 的四个答案,其中只有一个是正确的,请将正确答案的代号填在题后的
括号中.
1. 27 的立方根是( )
A.3 B. 3 C.9 D. 9
2. 下列计算中,正确的是( )
A. 2 4 6x x x B. 2 3 5x y xy
C. 3 2 6( )x x D. 6 3 2x x x
3. 长度单位 1 纳米 910 米,目前发现一种新型病毒直径为 25100 纳米,用科学记数法表
示该病毒直径是( )
A. 625.1 10 米 B. 40.251 10 米
C. 52.51 10 米 D. 52.51 10 米
4. 如图是由若干个小正方体块搭成的几何体的俯视图,小正方块中的数字表示在该位置
的小正方体块的个数,那么这个几何体的主视图是( )
A. B. C. D.
5. 下列图形中,既是轴对称图形又是中心对称图形的有( )
A.4个 B.3 个 C.2 个 D.1 个
1
2 3
俯视图
6. 把一个三角形改成和它相似的三角形,如果面积扩大 到原来的 100 倍,那么边长扩大
到原来的( )
A.10 倍 B.100 倍 C.1000 倍 D.10000 倍
7. 已知抛物线 2 1y x x 与 x 轴的一个交点为 ( 0)m, ,则代数式 2 2008m m 的值为
( )
A.2006 B.2007 C.2008 D.2009
8. 美是一种感觉,当人体下半身长与身高的比值越接近 0.618 时,越给
人一种美感.如图,某女士身高 165 cm;下半身长 x 与身高 l 的比值
是 0.60,为尽可能达到好的效果,她应穿的高跟鞋的高度大约为( )
A.4 cm B.6 cm
C.8 cm D.10 cm
9. 计算机中常用的十六进制是逢 16 进 1 的计数制,采用数字 0~9 和字母 A~F 共 16
个计数符号,这些符号与十进制的数的对应关系如下表:
十六进制 0 1 2 3 4 5 6 7 8 9 A B C D E F
十进制 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
例如,用十六进制表示:E + F = 1D,则用十六进制表示:A×E =( )
A.E0 B.10E C.EA D.8C
10. 如图,两个等腰 Rt△ABC、Rt△DEF 的斜边都为 4 2 cm,D、M 分别是
AB、AC 边上的中点,又 DE 与 AC(或 BC)交于点 P,当点 P 从 M 出发
以 1cm/s 的速度沿 MC 运动至 C 后又立即沿 CB 运动至 B 结束.若运动
时间为 t(单位:s),Rt△ABC 和 Rt△DEF 重叠部分的面积为 y(单位:
cm2),则 y 关于时间 t 的图像大致是( )
A. B. C. D.
x
l
(第 8 题图)
(第 10 题图)
A B
C D
E
(第 15 题图)
第 1 个 第 2 个 第 3 个
二、填空题:(本大题 6 个小题,每小题 4 分,共 24 分)在每小题中,请将答案直接填在题
后的横线上.
11. 分解因式: 2 9xy x .
12. 如图,AB//CD,BC//DE,则∠B+∠D = .
13. 某市出租车公司收费标准如图所示,如果小明乘此出租车最远能到达 13 千米处,那么
他最多只有 元钱.
(第 12 题图) (第 13 题图)
14. “上升数”是一个数中右边数字比左边数字大的自然数(如:
34,568,2469 等).任取一个两位数,是“上升数”的概
率是 .
15. 如图是由火柴棒搭成的几何图案,则第 10 个图案中有
__________________根火柴棒.
16. 一个商店以每 3 盘 16 元的价格购进一批录音带,又从另一个渠道以每 4 盘 21 元的价
格购进比前一批加倍的录音带,如果两种合在一起以每 3 盘 k 元的价格全部出售,可
得到投资 20%的收益,则 k 的值为_________________.
三、解答题:(本大题 4 个小题,每小题 6 分,共 24 分)解答时每小题必须给出必要的演算
过程或推理步骤.
17. 计算: 2009 2 01( 1) ( ) ( 3 ) 1 2sin602
18. 解不等式组: 1 3( 1) 8
5 4 2( 1)
x x
x x
19. 解方程: 2 233 3
x
x x
20. 青岛国际帆船中心要修建一处公共服务设施,使它到三所运动员公寓 A、B、C 的距离相等.
(1) 若三所运动员公寓 A、B、C 的位置如图所示,请你在图中确定这处公共服务设施
(用点 P 表示)的位置;
(2) 若∠BAC=66 ,则∠BPC= .
四、解答题:(本大题 4 个小题,每小题 10 分,共 40 分)解答时每小题必须给出必要的演
算过程或推理步骤.
A
B
C
21. 先化简,再求值
2
23 5( 2 )2 2
a a aa aa a
,其中 5 3a
22. 为了防控甲型 H1N1 流感,某校积极进行校园环境消毒,购买了甲、乙两种消毒液共 100
瓶,其中甲种 6 元/瓶,乙种 9 元/瓶.
(1) 如果购买这两种消毒液共用 780 元,求甲、乙两种消毒液各购买多少瓶?
(2) 该校准备再次..购买这两种消毒液(不包括已购买的 100 瓶),使乙种瓶数是甲种瓶
数的 2 倍,且所需费用不多于...1200 元(不包括 780 元),求甲种消毒液最多能再
购买多少瓶?
23. 已知:如图,一次函数的图像与反比例函数的图像交于 A、B 两点,过 A 作 AC x 轴
于点 C,已知 5OA , 2OC AC ,且点 B 的纵坐标为 3 .
(1) 求点 A 的坐标及该反比例函数的解析式;
(2) 求直线 AB 的解析式.
24. 如图,梯形 ABCD 中, //AB CD , AD CD , AC AB , 30DAC .点 E、F 是梯形
ABCD 外的两点,且 EAB FCB , ABC FBE , 30CEB .
(1) 求证: BE BF ;
(2) 若 5CE , 4BF ,求线段 AE 的长.
五、解答题:(本大题 2 个小题,第 25 小题 10 分,第 26 小题 12 分,共 22 分)解答时每小
题必须给出必要的演算过程或推理步骤.
25. 我市有一种可食用的野生菌,上市时,某经销公司按市场价格 30 元/千克收购了这种
野生菌 1000 千克存放入冷库中,据预测,该野生菌的市场价格 y(元)于存放天数 x
(天)之间的部分对应值如下表所示.
存放天数 x 天 2 4 6 8 10
市场价格 y 元 32 34 36 38 40
但冷冻存放这批野生菌时每天需要支出各种费用合计 310 元,而且这类野生菌在冷库
中最多保存 110 天,同时平均每天有 3 千克的野生菌损坏不能出售.
(1) 请你从所学过的一次函数、二次函数和反比例函数中确定哪种函数能表示 y 与 x
的变化规律,并直接写出 y 与 x 之间的函数关系式;若存放 x 天后,将这批野生
菌一次性出售,设这批野生菌的销售总额为 P 元,试求出 P 与 x 之间的函数关系
式;
(2) 该公司将这批野生菌存放多少天后出售可获得最大利润 w 元?并求出最大利润(利
润=销售总额-收购成本-各种费用)
(3) 该公司以最大利润将这批野生菌一次性出售的当天,再次按市场价格收购这种野
生菌 1180 千克,存放冷库中一段时间后一次性出售,其他条件不变,若要使两次
的总盈利不低于 4.5 万元,请你确定此时市场的最低价格应为多少元?
(结果精确到个位,参考数据: 14 3.742 , 1.4 1.183 )
26. 如图,在平面直角坐标系中,直线 3 3y x 与 x 轴交于点 A,与 y 轴交于点 C,抛
物线 2 2 3 ( 0)3y ax x c a 经过 A、B、C 三点.
(1) 求过 A、B、C 三点抛物线的解析式并求出顶点 F 的坐标;
(2) 在抛物线上是否存在点 P,使 ABP△ 为直角三角形,若存在,直接写出 P 点坐标;
若不存在,请说明理由;
(3) 试探究在直线 AC 上是否存在一点 M ,使得 MBF△ 的周长最小,若存在,求出 M
点的坐标;若不存在,请说明理由.
(命题人:刘 亮 审题人:沈丽容)
西南师大附中 2009—2010 学年度上期期末考试
初三数学 试题参考答案
一、选择题:(本大题 10 个小题,每小题 4 分,共 40 分).
题号 1 2[来 3 4 5 6 7 8 9 10
答案 A C D B B A D C D C
二、填空题:(本大题 6 个小题,每小题 4 分,共 24 分).
A O x
y
B
F
C
11. ( 3)( 3)x y y 12.180 13.16 14. 2
5
15 . 220
16.19
三、解答题:(本大题 4 个小题,每小题 6 分,共 24 分).
17.解:原式 1 4 1 |1 3 | ·········································································4 分
4 1 3 1 ·············································································· 5 分
4 3 ······················································································6 分
18.解: 1 3( 1) 8
5 4 2( 1)
x x
x x
①
②
由①得:1 3 3 8x x
3 8 4x x
2 12x
x < 6············································································ 3 分 由②得: 5 4 2 2x x 3 6x 2x ··············································································5 分 ∴ 原不等式组的解集为 2 6x ····························································6 分 19.解: 2 3( 3) 2x x 2 3 9 2x x 2 5x 5 2x ·················································································· 5 分 经检验: 5 2x 是原方程的解··································································· 6 分 20.(1) 作图略································································································ 4 分 (2) 132·····································································································6 分 四、解答题:(本大题 4 个小题,每小题 10 分,共 40 分)解答时每小题必须给出必要的演 算过程或推理步骤. 21.解:原式 2 33 4 5( )2 2 2 a a a a a a a a ······························································· 2 分 2 33 9 2 2 a a a a a a ·········································································· 4 分 ( 3) 2 2 ( 3)( 3) a a a a a a a ································································· 6 分 1 3a ························································································· 8 分 当 5 3a 时,原式 1 1 5 55 3 3 5 ············································ 10 分 22.解:(1) 设甲、乙两种消毒液各购买 x 瓶、y 瓶.············································· 1 分 根据题意得: 100 6 9 780 x y x y 解得 40 60 x y ····································4 分 答:甲种消毒液购买 40 瓶,乙种消毒液购买 60 瓶.····························· 5 分 (2) 设甲种消毒液购买 a 瓶,则乙种消毒液购买 2a 瓶.·······························6 分 由题意得: 6 9 2 1200a a 解得: 50a ················································································· 9 分 答:甲种消毒液最多能买 50 瓶.····················································· 10 分 23.解:(1) ∵ AC⊥x 轴,OC = 2AC, 5OA , ∴ 在 Rt△ACO 中,设 OC = a,AC = 2a,则 2 24 5a a ∴ 2 1a ,又 a > 0,则 a = 1.·······················································1 分
∴ 点 A 的坐标为(– 2,1)····························································2 分
设所求反比例函数的解析式为: ( 0)ky kx
········································3 分
∵ 点 A 在此反比例函数的图象上
∴ 1 2
k
∴ k = – 2 ················································································· 4 分
故所求反比例函数的解析式为: 2y x
···············································5 分
(2) 设直线 AB 的解析式为: y kx b ······················································ 6 分
∵ 点 B 在反比例函数 2y x
的图象上,点 B 的纵坐标为– 3,设 B(m,– 3).
∴ 2 23 3mm
, .
∴ 点 B 的坐标为( 2
3
,– 3).·························································7 分
由题意,得
1 2
23 3
a b
a b
··································································· 8 分
解得:
3
2
2
a
b
··············································································· 9 分
∴ 直线 AB 的解析式为: 3 22y x ················································ 10 分
24.(1) 证明:∵ 梯形 ABCD 中,AB∥CD,AD⊥CD,
∴ 90 30DAB DAC ,且
∴ 60BAC
∵ AB = AC,∴△ABC 为等边三角形
∴ AB = BC··················································································2 分
又∵∠ABC =∠FBE,∴ ∠ABE =∠CBF···············································3 分
在△ABE 和△CBF 中[
EAB FCB
AB CB
ABE CBF
∴ △ABE≌△CBF·········································································· 4 分
∴ BE = BF··················································································5 分
(2) 连接 EF
由(1)知△ABC 为等边三角形,∴ 60ABC [
又∵∠ABC =∠FBE,∴ 60FBE ····························································6 分
∵ BE = BF,△EBF 为等边三角形,
∴ 60BEF ,EF = BF········································································· 7 分
∵ 30CEB ,∴ 90CEF
∴ 在 Rt△CEF 中, 2 2 2 2 2CF CE EF CE BF ,
∵ CE = 5,BF = 4,∴ 41CF ····························································9 分
又由(1) △ABE≌△CBF 知,AE = CF.
∴ 41AE ······················································································· 10 分
五、解答题:(本大题 2 个小题,第 25 小题 10 分,第 26 小题 12 分,共 22 分)解答时每小
题必须给出必要的演算过程或推理步骤.
25.解:(1) 30y x ···················································································· 1 分[
( 30)(1000 3 )P x x
23 910 30000x x ····································································· 3 分
(2) 310 1000 39w P x
23 910 30000 310 1000 30x x x
23 600x x
23( 100) 30000x ····································································5 分
∵ 0 110x ,∴ 当 x = 100 时,利润 w 最大,最大利润为 30000 元,
∴ 该公司将这批野生菌存放 100 天后出售可获得最大利润 30000 元.········6 分
(3) 由(2)可知,该公司以最大利润出售这批野生菌的当天,市场价格为 130 元,
设再次进货的野生菌存放 a 天,则利润·················································7 分
1 ( 130)(1180 3 ) 310 130 1180w a a a
23 480a a ··············································································· 8 分
∴两次的总利润为 2
2 3 480 30000w a a
由 23 480 30000 45000a a ,解得 80 10 14a ································9 分
∵ 3 0 , ∴当80 10 14 80 10 14a 时,两次的总利润不低于 4.5 万
元,
又∵ 0 110 14 3.742x , ,∴当 43a 时,此时市场价格最低,市场最低价
格应 173 元.·················································································10 分
26.解:(1) ∵ 直线 3 3y x 与 x 轴交于点 A,与 y 轴交于点 C.
∴ ( 1 0)A , , (0 3)C , ·································································· 1 分
∵点 A,C 都在抛物线上,
2 30 3
3
a c
c
3
3
3
a
c
∴ 抛物线的解析式为 23 2 3 33 3y x x ········································ 3 分
∴ 顶点 4 3(1 )3F , ········································································ 4 分
(2) 存在
1(0 3)P , ······················································································ 6 分
2 (2 3)P , ······················································································8 分
(3) 存在
理由:延长 BC 到点 B,使 B C BC ,连接 B F 交直线 AC 于点 M,则点 M 就是
所求的点.
过点 B 作 B H AB 于点 H.
∵点在抛物线 23 2 3 33 3y x x 上,
∴ B(3,0)
在 Rt BOC△ 中, 3tan 3OBC ,
∴ 30OBC , 2 3BC ,在 Rt BB H△ 中, 1 2 32B H BB ,
3 6BH B H ,∴ OH = 3,∴ 'B (– 3, 2 3 )······························ 10 分
设直线 B F 的解析式为 y kx b ∴
2 3 3
4 3
3
k b
k b
解得
3
6
3 3
2
k
b
∴ 3 3 3
6 2y x
∴
3 3
3 3 3
6 2
y x
y x
解得
3
7
10 3
7
x
y
,
∴ 3 10 3
7 7M ( , )
∴在直线 AC 上存在点 M,使得 MBF△ 的周长最小,此时 3 10 3
7 7M ( , ).
································································································ 12 分
A O x
y
B
F
C
H
B M
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