山西省阳泉市平定县2020-2021学年七年级上学期期末数学试题（图片版）

$$ 平定县 2020—2021 学年第一学期期末教学质量检测 七年级数学参考答案 一、选择题（每小题 2 分，共 20 分） 题号 1 2 3 4 5 6 7 8 9 10 答案 C B D C D A B A C D 二、填空题（每小题 3 分，共 15 分） 11． 12．35 13．7.5 14．19 15．21 三、解答题（共 65 分） 16．解：（1）原式=－6－7－8+10·························································· 2 分 =－21+10·································································· 4 分 =－11．····································································5 分 （2） 原式=－27－ 9 2 2 3  + 6 1 2 －4 ·····················································7 分 =－27－ 3 1 + 3 1 －4 ·······························································8 分 =－27－4 ········································································ 9 分 =－31． ··········································································· 10 分 17． 解：去分母，得 2（2x－1）－（5x+1）=6．·································1 分 去括号，得 4x－2－5x－1=6．············································· 2 分 移项，得 4x－5x=6+2+1．················································3 分 合并同类项，得 －x=9．···························································4 分 系数化为 1，得 x=－9．·························································· 6 分 18．解：原式= 22233 2222  abbaabba ·····································2 分 = 22 4abba  ．································································ 3 分 当 a=1，b=－3 时， 原式= 22 )3(14)3(1  ·························································· 4 分 = 943  ···········································································5 分 =33． ················································································· 6 分 19．解：（1）分配···············································································2 分 （2）二························································································· 4 分 （3）原式 = ) 3 1 2 1 (4) 3 1 ()24( 8 1 )24(  = 6483  ································································ 5 分 =5+24 ··········································································· 6 分 =29 ．··························