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2007年四川省雅安市中考数学真题及答案.doc

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2007 年四川省雅安市中考数学真题及答案 本试卷分为第 I 卷(选择题)和第 II 卷(非选择题)两部分,第 I 卷 1 至 2 页,第 II 卷 3 至 8 页.全卷满分 120 分,考试时间 120 分钟. 第 I 卷(选择题 共 36 分) 注意事项: 1.在答第 I 卷之前,考生务必将自己的姓名、准考证号、考试科目等填涂在机读卡上. 2.每小题选出答案后,用 2B 或 3B 铅笔把机读卡上对应题目的答案标号涂黑,如需改动, 用橡皮擦擦干净后,再选涂其它答案,不能答在试卷上. 3.考试结束后,由监考人员将本试卷和机读卡一并收回. 一、选择题(本大题共 12 个小题,每小题 3 分,共 36 分)每小题的四个选项中,有且仅 有一个是正确的. 1. 8 的立方根是( ) A. 2 2  B. 2 C.  32 2 D. 3 2 2.下列运算正确的是( ) A. 2 a a  3 5 a B. 2 3 )a ( 5 a C. 6 2 a a  3 a D. 5 a  5 a  10 a 3.下列右图是由 5 个相同大小的正方体搭成的几何体,则它的俯视图在 A、B、C、D 中的选 项是( ) A. B. C. 4.若是直角三角形式一个锐角,sin   3 cos  ,则 D. 2 sin 3 题图 2sin     2 cos  cos   ( ) A.3 2 3  B. 1 2 3  2 5.已知二次函数 y  kx 2 6  x C. 2 2 3  D. 3  ,若 k 在数组{ 3 3   , , ,,,, 中随机取一个,则所得 11 2 3 4} 2 抛物线的对称轴在直线 1x  的右方时的概率为( ) B. 2 7 C. 4 7 A. 1 7 D. 5 7 6.在 ABC△ 中, D E, 分别是 AB AC, 边上的中点,则 S △ ADE : S 四边形 DBCE  ( )
A. 3 4 B. 1 4 C. 2 5 7.如图是坐标系的一部分,若 M 位于点 (2 D. 1 3 2), 上, N 位于 点 (4 2), 上,则G 位于点( )上. A.(1 3), B.(11), C.(0 1), D.( 11) , G M N ) D.675m2 C.650m2 B.625m2 8.为搞好环保,某公司准备修建一个长方体的污水处理池,池底矩形的周长为 100m,则池 底的最大面积是( A.600m2 9.如图,在平行四边形 ABCD 中, DE 是 ADC F 是 AB 的中点, ( ) A. 4 :1: 2 C.3:1: 2 10.已知不等式 ( B. 4 :1:3 D.5:1: 2 1) 2 x a 的平分线, : x   ,则( AD  ,则 : AE EF BE 为  的解集是 AB  , 6 EF ) C D A B 4 1 A. 3 a  B. a ≤ 3 C. 3 a  D. a   3 11.已知 M 是 ABC△ 的外心, ABC  60  , AC  ,则 ABC△ 4 A. 2 3 3 B. 2 3 C. 4 3 3 D. 5 3 3 12.如图,在 Rt ABC△ 中, ACB 为90 ,CD AB , cos A. BCD 9 10  , 2 3 B. 1 BD  ,则边 AB 的长是( 9 10 9 5 C.2 D. ) A 外接圆的半径是( ) C D B 第 II 卷(非选择题 共 84 分) 二、填空题(本大题共 5 个小题,每小题 3 分,共 15 分)请将答案直接写在相应题的横线 上. 13.234610000 用科学记数法表示为 14.观察一组数 2、5、11、23、( )、95、…,括号内的一个数应该是 (保留三个有效数字). . 15.分解因式 22 x 3 x 1   . 16.如图, AD 是 ABC△ 的中线, ADC  45  , BC  2cm ,把 ACD△ 沿 AD 对折,
使点C 落在 E 的位置,则 BE  cm. E D A C B 17.某体育场的环行跑道长 400 米,甲、乙同时从同一起点分别以一定的速度练习长跑和骑 自行车.如果反向而行,那么他们每隔 30 秒相遇一次.如果同向而行,那么每隔 80 秒乙就 追上甲一次.甲、乙的速度分别是多少?设甲的速度是 米/秒,乙的速度是 y 米/秒.则列 出的方程组是 三、解答题(本大题共 8 个小题,共 69 分)要求写出必要的解答过程或演算步骤. 18.(每小题 5 分,共 10 分) . (1)计算: cos60  |1   3 | (2 tan 30 )         12   5  . (2)先化简,再求值: 2 a  b ab 2 a  2 b  ab  2 a b a  2 ab b   2 (其中 3 a  , b  ). 1 2 19.(本小题 6 分) 解不等式组 1 2 x    1 x   4  2 ≤ , x 3 , 并将其解集表示在数轴上. 20.(本小题 7 分) 2 x 解方程 x  1 x  0  3 2 .  x 21.(本小题 8 分) 袋中有 2 个红球、1 个白球,它们除颜色外完全相同. (1)求从袋中任意取出 1 球是红球的概率; (2)先从袋中任意取出 1 球,然后放回,再从袋中任意取出 1 球,请用画树状图或列表格 法求两次都取到红球的概率.
22.(本小题 8 分) 某班要从甲、乙、丙三名候选人中选出一名参加学校组织的知识竞赛.班上对三名候选人进 行了笔试和口试两次测试,测试成绩如下表: 测试项目 笔试 口试 甲 70 90 测试成绩(分) 乙 80 70 丙 85 65 班上 50 名学生又对这三名候选人进行了民主投票,三人的得票率(没有弃权票,每位学生 只能投三人中的一票)如下图,每得一票记 1 分. (1)请分别算出三人的得票分; (2)如果根据三项得分的平均成绩高者被当选,那么谁将被当选(精确到 0.01)? (3)如果根据笔试、口试、投票三项成绩按 5∶3∶2 的比例确定成绩,根据成绩的加权平 均数高者当选,那么谁又将被当选? 23.(本小题 8 分) 甲 30% 丙 40% 乙 30%  ( 0 k  )图象经过点 (1 2), ,并与直线 2  y ( A x x b  交于点 1 y, , ) 1 如图,反比例函数 y k x y, ,且满足 1 x 2 ) ( 2 ( B x  x 2 )(1  x x 1 2 ) 3  . (1)求 k 的值; (2)求b 的值及点 A B, 的坐标. y O B A x 24.(本小题 10 分) 如图,已知 AB 是 O 的直径,直线CD 与 O 相切于C 点, AC 平分 DAB (1)求证: AD CD ; . (2)若 AD  , 2 AC  ,求 O 的半径 R 的长. 6 D 3 4 C 2 1 A O B
25.(本小题 12 分) 如图,已知 OAB△ 的顶点 (3 0) A , , (0 1) B , ,O 是坐标原点.将 OAB△ 绕点O 按逆时针旋 ODC△ 转 90°得到 (1)写出C D, 两点的坐标; (2)求过C D A, , 三点的抛物线的解析式,并求此抛物线的顶点 M 的坐标; (3)在线段 AB 上是否存在点 N 使得 NA NM 请说明理由. ?若存在,请求出点 N 的坐标;若不存在, M y D B O C x A 四川省雅安市二○○七年高中阶段教育学校招生考试 数学试题参考答案及评分意见 一、选择题 1~5.BACCB 二、填空题 6~10.DCBAD 11~12.CD 13. 2.35 10 8 14.47 15.(2 x  1)( x  1) 16. 2 17. 30(   80(  x y   ) y ) x   , 400 400 三、解答题 18.(10 分) (1)解:原式   1 2 ( 3 1)   2      3 3      5 2 ······················································· 3 分   1 2  4 3 3 3 1 2    3 3  ··························································· 4 分 5 2 .················································································· 5 分 (2)解:原式   ) ( a a b  b (  a b a b   )( ab )  b a  ( ) a b  2 ············································· 2 分 ) ( a a b  b  ( ab )( a b a b   b a  ) a b  ( 2  ) ············································· 3 分
 2 a a b   1 a b   2 1 a  a b  ···················································································4 分 当 3 a  , b  时, 1 2 2 3 3  原式  2 1 a  a b  19.(6 分)  1 16  1 5 2  .·············································································5 分 解: 2 1 x    1 x   4 2 ≤ , x 3  ···························································································· 1 分 2 3 x  ≤   3( 1) x   ≤ 4 x ··························································································· 2 分 ≤ , 3  x   2    3 x  ··································································································· 3 分    ≤ .···························································································· 4 分 3 x 3 2 3   2 1 0  1 3 2 2 20.(7 分) 解:将原方程去分母得 ·································································· 6 分 22 x  2( x  1)( x  2) 3 ( x x  1)  ········································································ 2 分     ··························································································· 3 分 x 4 0 23 x   (3 x 4)( x 1) 0   4 3 x  或 1 x  或 x   ·························································································· 5 分 4 3 x   ,都是方程的解.····························································· 6 分 经检验 1
所以原方程的解为 x  或 4 3 x   .··································································· 7 分 1 21.(8 分) 解:(1)任意取出 1 球的取法有 3 种,其中是红球的取法有 2 种.····························1 分 则任意取出 1 球是红球的概率为 2 3 .···································································3 分 (2)依题意,任意取出 1 球,然后放回,再从中任意取出 1 球的树状图如下: 则两次都取到红球的概率为 4 9 .········································································· 8 分 ···························6 分 22.(8 分) 解:(1)三人的得票分分别为 甲:50 30% 15 乙:50 30% 15 丙:50 40% 20 (2)三项得分的平均成绩     分  分  分······················································································ 3 分 70 90 15   3 80 70 15   3 85 65 20   甲: 乙: 丙: ≈ 58.33  55.00 ≈ 56.67 3 由题意得甲将被当选.····················································································· 6 分 (3)由题意三人的平均得分分别为 甲: 乙: 丙: 5 70 3 90 2 15    5 80 3 70 2 15      5 3 2     5 3 2     5 3 2   5 85 3 65 2 20     65  64  66 k 1 (2)由题意 所以丙将被当选.····························································································8 分 23.(8 分) 解:(1)反比例函数 y  ( 0 k  )图象经过点 (1 2), , k x     .························································································· 2 分 2 k 2
  y    y  , 2 x 2 x b     x b 2 2 x   22 x bx   2 0 ①···············································································4 分 x 1  x 2     1 ·················································································· 5 分 b    (无“  ”可不扣分) 2 16 0  b 2 )(1 ,  x 2 x x 1 2  (1 1) 3   x x 1 2 ) 3  x 则由 1 (   b  2     3 b   .··································································································· 6 分 ①为 22 x 3 x   x 1 2  , x 2 2 0   1 2 1 1 y    , y 4 . 即 (2 1) A , , B     1 2  , .··············································································· 8 分 4    24.(10 分) 解:(1)连接OC , 直线CD 与 O 相切于C 点, AB 是 O 的直径,  又 AC 平分 DAB      OC CD  DAB , . 2 .······················································ 1 分     DAB ,··································· 3 分 1 1 2 2 1 又  ∥ ,   AD OC AD CD COB  D 3 4 C 2 1 A O B .······························································································· 4 分 (2)又连接 BC ,则 在 ADC△ 和 ACB△ ACB  90  , 中 2 1     ADC △ AD AC  R AC  2 , 3    ACB ∽△  90  ,·····································································6 分 ACB .·····················································································7 分 ··································································································9 分
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