[]辽宁省锦州市2019-2020学年八年级上学期期末考试数学试题（图片版)

八年级数学试题答案 第 1 页 (共 5 页) 2019—2020学年度八年级（上）期末质量检测 数学试题参考答案及评分标准 注：若有其他正确答案请参照此标准赋分. 一、选择题（本题共 8个小题,每小题 2分，共 16分） 选择题号 1 2 3 4 5 6 7 8 选项 D B D A B C B C 二、填空题（本题共 8个小题,每小题 2分，共 16分） 9． 3 2  10．（7，5） 11．y1<y2 12． 乙 13．       2, 3 2 14      315%11%10 ,3000 yx yx 15. (－6，0)，（ 2 3 ，0） 16. 2 1 2 3   n n （或 1 2 3 2         n 或 15.12  n 等其他写法也给分） 三、解答题（本大题共 2 个题，17 题 8 分，18 题 6 分，共 14 分） 17．解：（1）原式＝3 2 +2 3 ﹣2 2 +3 3 ························································ 2 分 ＝ 2 +5 3 ； ································································································ 4 分 （2）原式＝（2 2 ） 2 ﹣（ 5 ） 2 ············································································· 2 分 ＝8﹣5 ·············································································································· 3 分 ＝3． ················································································································ 4 分 18.      .53 ,94 yx yx 方法一：解：①+② ，得 7x＝14. ······································································ 3 分 解得 x＝2.··································································································· 4 分 将 x＝2 代入②，得 y＝1. ········································································ 5 分 所以原方程组的解是      .1 ,2 y x ·································································· 6 分 方法二：解：由①，得 y＝9－4x . ③ ······················································· 1 分 将③代入②，得 3x－（9－4x）＝5. ······················································ 3 分 解得 x＝2. ···························································································· 4 分 将 x＝2 代入③，得 y＝1. ········································································· 5 分 ① ② 八年级数学试题答案 第 2 页 (共 5 页) 所以原方程组的解是      .1 ,2 y x ··································································· 6 分 四、解答题（本大题共 3 个题，19，20 各 6 分，21 题 8 分，共 20