湖北咸宁通山2020-2021学年九年级上学期期末数学试卷及答案

$$ 九年级数学试题答案 第 1 页（共 6 页） 通山县 2020 年秋期末考试九年级数学试题 参考答案及评分说明 说明： 1．如果考生的解答正确，思路与本参考答案不同，可参照本评分说明制定相应的评分细 则评分． 2．每题都要评阅完毕，不要因为考生的解答中出现错误而中断对该题的评阅．当考生的 解答在某一步出现错误，影响了后继部分时，如果该步以后的解答未改变这道题的内容和难度， 则可视影响的程度决定后面部分的给分，但不得超过后面部分应给分数的一半；如果这一步以 后的解答有较严重的错误，就不给分． 3．为阅卷方便，解答题的解题步骤写得较为详细，但允许考生在解答过程中，合理地省 略非关键性的步骤． 4．解答右端所注分数，表示考生正确做到这一步应得的累加分数． 5．每题评分时只给整数分数． 一、选择题（每小题 3 分，共 24 分） 二、填空题（每小题 3 分，共 24 分） 9．答案不唯一，如 1 y x  10． ( 2, 3)  11． 2 5 12．（3， 2 ） 13． 25000(1 ) 7500x  14．36 15． 13 2 16．①②④ 三、解答题（共 72 分） 17．解： 1a  ， 6b   ， 1c   ····························································································· 2 分 2 4 40b ac  ， ·········································································································· 4 分 2 4 6 2 10 2 2 b b ac x a       ∴ 1 3 10x   ， 2 3 10x   . ················································································ 7 分 18．解：（1）把 A（6，1）代入 2 m y x  ，得1 6 m  ，解得 m=6. 题号 1 2 3 4 5 6 7 8 答案 D A D B D A C A 九年级数学试题答案 第 2 页（共 6 页） ∴ 2 6 y x  . ·········································································································· 1 分 把 B（a，-3）代入 2 6 y x  ，得 6 3 a   ，解得 2a   . ∴B（ 2 ，-3）. ······························································································ 2 分 把 A（6，1），B（ 2 ，-3）代入 1y kx b  ，得 1 6 3 2 . k b k b        ， 解得 1 = 2 = 2. k b      ， ∴ 1 1 2 2 y x  . ·································································································· 5 分 （2） x   或 0 x  ． ·························································································· 8 分 19．解：（1） 1 3 . ··························································································································· 2 分