福建省福州市2019-2020学年八年级下学期期末考试数学试题（图片版）

八年级数学试题答案及评分参考第 1 页（共 4 页） 数学试题答案及评分参考 评分说明： 1．本解答给出了一种或几种解法供参考，如果考生的解法与本解答不同，可根据试题的主要考 查内容比照评分参考制定相应的评分细则． 2．对于计算题，当考生的解答在某一步出现错误时，如果后继部分的解答未改变该题的内容和 难度，可视影响的程度决定后继部分的给分，但不得超过该部分正确解答应给分数的一半； 如果后继部分的解答有较严重的错误，就不再给分． 3．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． 4．只给整数分数．选择题和填空题不给中间分． 一、选择题：共10小题，每小题4分，满分40分；在每小题给出的四个选项中，只有一项是符合题目要求的，请 在答题卡的相应位置填涂． 1．A 2．C 3．B 4．D 5．B 6．D 7．C 8．B 9．B 10．A 二、填空题：共6小题，每小题4分，满分24分，请在答题卡的相应位置作答． 11．50 12． 34 13．＞ 14．70 15．6 16．6 三、解答题：共9小题，满分86分，请在答题卡的相应位置作答． 17．（本小题满分8分） 解：原式  2 2  1  2  2 2  1 ························································································ 6 分  2． ················································································································· 8 分 18．（本小题满分8分） 解：（1）将（1，4）代入 y  kx  2（k≠0）， 得 k  2  4， ······································································································· 2 分 解得 k  2， ········································································································· 3 分 则该一次函数的解析式为 y  2x  2． ········································································ 4 分 x  1 0 y 0 2 该一次函数的图象如图所示： ································································ 6 分 （2）由图象可得，当 y≤0 时，x≤  1． ·········································································· 8 分 4 3 2 1 －1 －2 －2 －1 21 3 x y O 2 2y x  八年级数学试题答案及评分参考第 2 页（共 4 页） 19．（本小题满分8分） 解：（1） ································································ 3 分 如图，射线 BC，线段 BD 即为所求作； ···································································· 4 分 （2）解：由（1）得 BD∥OA，BD  OA， ∴四边形 OBDA 是平行四边形． ······································································· 5 分 ∵OA  OB， ∴平行四边形 OBDA 是菱形， ·········································································· 6 分 ∴DE  1 2 OD，AB⊥OD． ················································································ 7 分 ∵OD