2020-2021学年山东省济南市高新区七年级第一学期期中数学试卷参考答案及评分标准

2020-2021学年山东省济南市高新区七年级第一学期期中数学试卷参考答案及评分标准

第1页（共2页） 2020 至 2021 学年第一学期期中学业水平测试 高新初中数学七年级参考答案及评分标准 一、选择题 题号 1 2 3 4 5 6 7 8 9 10 11 12 答案 B C B A C A C C D D D C 二、填空题:（本大题共 6 个小题，每小题 4 分，共 24 分．） 13．＞ 14．﹣4 15．① 16．2 17．4b﹣2a 18．556 三、解答题:（本大题共 12 个小题，共 78 分．解答应写出文字说明、证明过程或演算步骤．） 19．（本题 4 分）解：原式＝9+1﹣10·····················································································3 分 ＝0·····························································································4分 20．（本题 4 分）解：原式= 25 × (− 1 5) × 1 5 × (− 4 3) ·································································2 分 = 4 3．···························································································4 分 21．（本题 4 分）解：原式＝（5﹣1）m+（2﹣3）n··································································2 分 ＝4m﹣n······················································································4 分 22．（本题 5 分）解：﹣14﹣8+（﹣2）3×（﹣3） ＝﹣1﹣8+（﹣8）×（﹣3）········································································2 分 =-1-8+24································································································3 分 ＝15······································································································5分 23．（本题 5 分）解：原式＝x+6y2﹣4x﹣8x+4y2·······································································4 分 ＝10y2﹣11x···································································································5 分 24．（本题 6 分）解：所画图形如下所示： ························································································6 分 25．（本题 6 分）解：∵a※b＝（a+b）+（a﹣b）， ∴13※5 ＝（13+5）+（13﹣5）···································································································4 分 ＝26···························································································································6分 26．（本题 6 分）解：原式＝2x﹣4y﹣x+2y+2x ＝3x﹣2y····················································································4 分 当 x＝﹣4，y＝3 时，原式＝﹣12﹣6＝﹣18········································································6 分 27．（本题 8 分）解：（1）（ +65+68+50+66+50+75+74）+（﹣60﹣64﹣63﹣58﹣60﹣64﹣65）········2 分 ＝14（元）·····················································································3 分 答：到这个周末，小李有 14 元的节余．············································································4 分 （2）1 7（|﹣60|+|﹣64|+|﹣63|+|﹣58|+|﹣60|+|﹣64|+|﹣65|）······················································5 分 ＝62（元）···············································································································6 分 62×30＝1860（元）·······································································································7 分 答：小李一个月（按 30 天计算）至少要有 1860 元的收入才能维持正常开支．···························8 分 第2页（共2页） 28．（本题 8 分）解：（1）原式= 1 3 ×12− 1 6 ×12+ 1 2 ×12 ＝4﹣2+6················································································3 分 ＝8························································································4 分 （2）原式的倒数是：（3 4 − 5 26 + 1 2 − 2 13）×（﹣52）····························································6 分 =﹣39+10﹣26+8 ＝﹣47·····························································································7 分 故原式= − 1 47．···········································································································8 分 29．（本题 10 分）解：（1）答案为 6，4···············································································2 分 （2）答案为 5t，3t．·····································································································4 分 （3）t＝3．················································································································6 分 （4）由题意：6+3t﹣5t＝5 或 5t﹣（6+3t）＝5···································································8 分 解得 t= 1 2或11 2 ， ∴t 的值为1 2或11 2 秒时，线段 AB 的长为 5···········································································10 分 30．（本题 12 分）解：（1）答案为(2 −1 12 2 )·········································································3 分 （2）答案为(1 8 −5 0)；··································································································6 分 （3） 销售额 总利润 门店 1 5900 1380 门店 2 5175 1165 ······························································································································10 分 (80 25 120 45 30 85 ) × ( 20 5 100 20 15 4 ) = (80 × 20 + 25 × 100 + 120 × 15 80 × 5 + 25 × 20 + 120 × 4 45 × 20 + 30 × 100 + 85 × 15 45 × 5 + 30 × 20 + 85 × 4 ) = (5900 1380 5173 1165) ·······································································································12 分 声明：试题解析著作权属菁优网所有，未经书面同意，不得复制发布 日期：2020/10/7 21:33:06；用户：张老师；邮箱：zhangzhao@xyh.com；学号：37304035