2009 年重庆中考数学真题及答案
(本卷共五个大题,满分 150 分,考试时间 120 分钟)
参考公式:抛物线
y
2
ax
bx
( 0a )的顶点坐标为
c
b
2
a
4
,
2
ac b
4
a
,对称轴公
式为
x
.
b
2
a
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. 5 的相反数是(
B. 5
A.5
)
C. 1
5
D. 1
5
2.计算 3
2x
2
x 的结果是(
)
A. x
C. 52x
D. 62x
B. 2x
1
3
x
3.函数
y
3
x
的自变量 x 的取值范围是(
3
x
3
x
B.
C.
)
A
x
C.90°
D.100°
3
≥
100
°,
AB∥ .若
D.
AEC
)
B.80°
A.
4.如图,直线 AB CD、 相交于点 E , DF
则 D 等于(
A.70°
5.下列调查中,适宜采用全面调查(普查)方式的是(
A.调查一批新型节能灯泡的使用寿命
B.调查长江流域的水污染情况
C.调查重庆市初中学生的视力情况
D.为保证“神舟 7 号”的成功发射,对其零部件进行检查
6.如图, O⊙ 是 ABC△
则 A 等于(
A.60°
7.由四个大小相同的正方体组成的几何体如图所示,那么它的左视图是(
的外接圆, AB 是直径.若
°,
BOC
B.50°
C.40°
D.30°
80
)
)
B
B
F
C
E
D
4 题图
A
C
O
6 题图
)
A.
B.
C.
8.观察下列图形,则第 n 个图形中三角形的个数是(
D.
)
正面
7 题图
2n
A. 2
4n
9.如图,在矩形 ABCD 中,
第 1 个
B. 4
C. 4
2
AB ,
第 2 个
4n
1
BC ,动点 P从点 B出发,
第 3 个
……
D. 4n
D
A
9 题图
C
P
B
作匀速运动,那么 ABP△
沿路线 B
的路程 x 之间的函数图象大致是(
D
C
的面积 S与点 P运动
)
S
3
S
3
1
O
1
A.
S
1
O
3
x
S
2
1
O
3
x
1
D.
1
3
x O
3
x
B.
中,
C.
AC
°,
8
C
90
是等腰直角三角形;
10.如图,在等腰 Rt ABC△
,F是 AB边上的中点,点 D、E分别
在 AC、BC边上运动,且保持 AD CE .连接 DE、DF、EF.在此运动变化的过程中,下列
结论:
① DFE△
②四边形 CDFE不可能为正方形,
③DE长度的最小值为 4;
④四边形 CDFE的面积保持不变;
⑤△CDE面积的最大值为 8.
其中正确的结论是(
A.①②③
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.据重庆市统计局公布的数据,今年一季度全市实现国民生产总值约为 7840000 万元.那
么 7840000 万元用科学记数法表示为
B.①④⑤
C.①③④
D.③④⑤
10 题图
万元.
)
D
C
E
B
A
F
12.分式方程 1
1
x
13 . 已 知 ABC△
与 DEF△
为
2
.
1
x
的解为
.
相 似 且 面 积 比 为 4 ∶ 25 , 则 ABC△
与 DEF△
的 相 似 比
14.已知 1O⊙ 的半径为 3cm, 2O⊙ 的半径为 4cm,两圆的圆心距 1
2O O 为 7cm,则 1O⊙ 与 2O⊙
的位置关系是
.
3
.现将背面完
的 5 张卡片洗匀后,背面朝上,从中任取一张,
x 与两坐标轴围成一个 AOB△
、 1
3
15.在平面直角坐标系 xOy 中,直线
y
全相同,正面分别标有数 1、2、3、 1
2
将该卡片上的数作为点 P的横坐标,将该数的倒数作为点 P的纵坐标,则点 P落在 AOB△
内的概率为
16.某公司销售 A、B、C三种产品,在去年的销售中,高新产品 C的销售金额占总销售金额
的 40%.由于受国际金融危机的影响,今年 A、B两种产品的销售金额都将比去年减少 20%,
因而高新产品 C是今年销售的重点.若要使今年的总销售金额与去年持平,那么今年高新产
品 C的销售金额应比去年增加
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:
| 2 |
1
1
3
(π
0
2)
9 ( 1)
2
.
18.解不等式组:
x
3(
3 0
1)
x
≤
,
2
①
x
1
. ②
19.作图,请你在下图中作出一个以线段 AB为一边的等边 ABC△
并写出已知、求作,保留作图痕迹,不写作法和结论)
.(要求:用尺规作图,
已知:
求作:
A
19 题图
B
20.为了建设“森林重庆”,绿化环境,某中学七年级一班同学都积极参加了植树活动,今
年 4 月该班同学的植树情况的部分统计如下图所示:
植树 2 株的
人数占 32%
人数
16
9
1
2
4
16
14
12
10
8
6
4
2
0
20 题图
7
5
4
6 植树量(株)
(1)请你根据以上统计图中的信息,填写下表:
该班人数
植树株数的中位数
植树株数的众数
(2)请你将该条形统计图补充完整.
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.先化简,再求值:
1
1
2
x
2
x
1
2
x
2
x
4
,其中
x .
3
22.已知:如图,在平面直角坐标系 xOy 中,直线 AB分别与 x
y、 轴交于点 B、A,与反比
例函数的图象分别交于点 C、D,CE
x⊥ 轴于点 E,
tan
ABO
(1)求该反比例函数的解析式;
(2)求直线 AB的解析式.
1
2
,
OB
4
,
OE
2
.
y
A
O
C
E
22 题图
B
D
x
23.有一个可自由转动的转盘,被分成了 4 个相同的扇形,分别标有数 1、2、3、4(如图
所示),另有一个不透明的口袋装有分别标有数 0、1、3 的三个小球(除数不同外,其余都
相同),小亮转动一次转盘,停止后指针指向某一扇形,扇形内的数是小亮的幸运数,小红
任意摸出一个小球,小球上的数是小红的吉祥数,然后计算这两个数的积.
(1)请你用画树状图或列表的方法,求这两个数的积为 0 的概率;
(2)小亮与小红做游戏,规则是:若这两个数的积为奇数,小亮赢;否则,小红赢.你认
为该游戏公平吗?为什么?如果不公平,请你修改该游戏规则,使游戏公平.
1
4
2
3
23 题图
A
D
F
24.已知:如图,在直角梯形 ABCD中,AD∥BC,∠ABC=90°,DE⊥AC于点 F,交 BC于点 G,
交 AB的延长线于点 E,且 AE AC
(1)求证: BG FG ;
(2)若
,求 AB的长.
.
AD DC
2
B
E
G
C
24 题图
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.某电视机生产厂家去年销往农村的某品牌电视机每台的售价 y(元)与月份 x之间满足
函数关系
y
50
x
2600
,去年的月销售量 p(万台)与月份 x之间成一次函数关系,其
中两个月的销售情况如下表:
月份
销售量
1 月
3.9 万台
5 月
4.3 万台
(1)求该品牌电视机在去年哪个月销往农村的销售金额最大?最大是多少?
(2)由于受国际金融危机的影响,今年 1、2 月份该品牌电视机销往农村的售价都比去年
12 月份下降了 %m ,且每月的销售量都比去年 12 月份下降了 1.5m%.国家实施“家电下乡”
政策,即对农村家庭购买新的家电产品,国家按该产品售价的 13%给予财政补贴.受此政策
的影响,今年 3 至 5 月份,该厂家销往农村的这种电视机在保持今年 2 月份的售价不变的情
况下,平均每月的销售量比今年 2 月份增加了 1.5 万台.若今年 3 至 5 月份国家对这种电视
机的销售共给予了财政补贴 936 万元,求 m 的值(保留一位小数).
(参考数据: 34
5.831≈
, 35
5.916≈
, 37
6.083≈
, 38
6.164≈
)
26.已知:如图,在平面直角坐标系 xOy 中,矩形 OABC的边 OA在 y轴的正半轴上,OC在
x轴的正半轴上,OA=2,OC=3.过原点 O作∠AOC的平分线交 AB于点 D,连接 DC,过点 D
作 DE⊥DC,交 OA于点 E.
(1)求过点 E、D、C的抛物线的解析式;
(2)将∠EDC绕点 D按顺时针方向旋转后,角的一边与 y轴的正半轴交于点 F,另一边与线
段 OC交于点 G.如果 DF与(1)中的抛物线交于另一点 M,点 M的横坐标为 6
5
,那么 EF=2GO
是否成立?若成立,请给予证明;若不成立,请说明理由;
(3)对于(2)中的点 G,在位于第一象限内的该抛物线上是否存在点 Q,使得直线 GQ与
AB的交点 P与点 C、G构成的△PCG是等腰三角形?若存在,请求出点 Q的坐标;若不存在,
请说明理由.
y
A
EE
O
D
B
x
C
26 题图
数学试题参考答案及评分意见
3.C
4.B
5.D
6.C
7.A
8.D
9.B
10.B
一、选择题
1.A
2.B
二、填空题
11.
7.84 10
6
12.
3
x
13. 2:5
14.外切
15. 3
5
16.30
三、解答题
17.解:原式 2 3 1 3 1
18.解:由①,得
由②,得
所以,原不等式组的解集为 3
····································································· (5 分)
3 .··················································································· (6 分)
x .·········································································(2 分)
x ≤ .··········································································(4 分)
≤ .·········································· (6 分)
19.解:已知:线段 AB .··········································································(1 分)
求作:等边 ABC△
.················································································ (2 分)
作图如下:(注:每段弧各 1 分,连接线段 AC BC、 各 1 分)
3
2
x
2
C
A
B
20.解:(1)填表如下:
·······························································(6 分)
该班人数
植树株数的中位数 植树株树的众数
50
(2)补图如下:
人数
16
14
12
10
8
6
4
2
0
16
14
9
1
2
4
3
7
5
四、解答题:
21.解:原式
x
2 1
2
x
(
1)
x
2)(
x
(
x
2
2)
2
·············································· (4 分)
4
6 植树量(株)
·························(6 分)
······················································· (4 分)
x
x
x
1 (
2
2)(
x
(
1)
x
2
2)
··············································································· (6 分)
.································································································(8 分)
5
2
.······························································(10 分)
2
,
BE .
2 4 6
3
当
2
1
x
x
x 时,原式 3 2
3 1
4
OE
,
22.解:(1)
⊥ 轴于点 E .
1
2
2 3
x
ABO
CE
tan
OB
CE
BE
点C 的坐标为
C , .········································································ (2 分)
CE .·························································· (1 分)
,
3
(
m
0)
.
设反比例函数的解析式为
my
x
m
,··································································(3 分)
2
将点C 的坐标代入,得3
m .····························································································· (4 分)
.···························································(5 分)
该反比例函数的解析式为
6
y
6
x
(2)
OB
4
, (4 0)
B , .····································································· (6 分)
tan
ABO
OA
OB
1
2
,
OA , (0 2)
A , .············································································· (7 分)
2
设直线 AB 的解析式为
y
(
kx b k
.
0)
将点 A B、 的坐标分别代入,得
b
4
2
,
k b
0.
·················································· (8 分)
解得
1
2
k
2.
b
,
··························································································(9 分)
直线 AB 的解析式为
1
2
23.解:(1)画树状图如下:
y
x
.·························································(10 分)
2
幸运数
吉祥数
积
1
1
1
0
0
或列表如下:
幸运数
积
2
1
2
3
1
3
4
1
3
4
12
3
9
0
0
3
6
0
0
3
3
0
0
···················· (4 分)
1
2
3
4
吉祥数
0
1
3
0
1
3
0
2
6
0
3
9
0
4
12
·············································································································· (4 分)
由图(表)知,所有等可能的结果有 12 种,其中积为 0 的有 4 种,
所以,积为 0 的概率为
P
.···························································· (6 分)
(2)不公平.·························································································· (7 分)
因为由图(表)知,积为奇数的有 4 种,积为偶数的有 8 种.
,·························································(8 分)
1
3
.································································· (9 分)
4
12
1
3
4
P
12
2
3
8
12
所以,积为奇数的概率为 1
P
积为偶数的概率为 2
因为 1
3
2
3
,所以,该游戏不公平.
G
C
B
E
游戏规则可修改为:
若这两个数的积为 0,则小亮赢;积为奇数,则小红赢.································· (10 分)
(只要正确即可)
ABC
°, ⊥ 于点 F ,
AFE
.································· (1 分)
EAF
,
AFE
≌△
CAB
DE
AC
90
D
A
F
,
AB AF
24.(1)证明:
ABC
AC AE
ABC
△
·································· (2 分)
.·········································· (3 分)
连接 AG ,··············································· (4 分)
AG AG AB AF
Rt
ABG
△
BG FG
(2)解: AD DC DF
,
Rt
.·······················(5 分)
≌ △
.·········································· (6 分)
, ⊥ ,
,
AFG
AC
AF
1
AC
2
E °.
E
FAD
AE
.············································································ (7 分)
1
2
30
°,············································································· (8 分)
30
AF .···························································································(9 分)
3
AB AF
.················································································· (10 分)
3
五、解答题:
25.解:(1)设 p 与 x 的函数关系为
p
(
kx b k
,根据题意,得
0)
k b
5
k b
3.9
,
4.3.
·························································································· (1 分)