山东省济南市长清区2020-2021学年七年级上学期期末考试数学试题（扫描版）

$$ 第 1 页(共 4 页) 七年级数学试题参考答案与评分标准（2021.1） 一、选择题 题号 1 2 3 4 5 6 7 8 9 10 11 12 答案 B D D B C A B A C C D C 二、填空题 13. －3 14. －2 15. 3 16. 75 17. 71 18. 202120202 a 三、解答题 19.解：(1)原式=11+9 ········································································ 1 分 =20 ··········································································· 2 分 (2)原式= 1 2 24 24 6 3          ····························································· 3 分 = －4+16 ····································· 5 分 (每算对一个得数得 1 分) =12 ·················································································· 6 分 20.解： 解：(1)如图，射线 AB 即为所求． (2)如图，直线 BC 即为所求． (3)如图，连接 AC 交直线 l 于点 E，点 E 即为所求． 注：画图 3 分（各 1 分），结论各 1 分（三个结论分开写或一起写，只要都有得 3 分）. 21.解：2（2a2－a）－（4a2－4a+1） ＝4a2－2a－4a2+4a－1······································································2 分 ＝2a－1，······················································································ 3 分 第 2 页(共 4 页) 当 1 2 a   时， 原式= 1 2 1 2         ················································································ 4 分 =－1－1·····························································································5 分 =－2································································································· 6 分 22.解：(1)3 5 6 2x x   ······································································1 分 8 8x  ，········································································ 2 分 x＝1．········································································· 3 分 (2)    3 3 2 2 5 6x x    ······································································ 4 分 9 6 2 10 6x x    ······································································ 5 分 9 2 6 6 10x x    ····································································· 6 分 7x＝－10，···············································································7 分 10 7 x   ．········································