上海市普陀区2024-2025学年八年级上学期期末考试数学试题（含答案）

2024 学年度第一学期期末八年级自适应练习数学学科 参考答案与评分建议 2025.1 一、单项选择题（本大题共 6小题，每题 2 分，满分 12分） 1．(C) 2．(B) 3．(A) 4．(D) 5．(C) 6．(B) 二、填空题（本大题共有 12 题，每题 3 分，满分 36 分） 7． 2a 2a ； 8． x1 0，x2 1； 9． x 2 ； 1 10． ； 11． (x 1 2)(x 1 2)； 12．5 ； 2 13．10(1 x)2 19.6； 14．真； 15．35； 1 1 3 16．55； 17． ； 18． 或 ． 2 4 4 说明：18 题答对 1 个解给 2 分. 三、简答题（本大题共 4 题，每题 6 分，满分 24 分） 2 3 1 19．解：原式= 2 ······································ （1+1+1 分） 2 3 2 3 27 3 = 2 2 3 ····························································（1+1 分） 9 8 = 2 2 3 ． ····································································· （1 分） 9 说明：没有过程扣 3 分. 2 20．解： x 2(x 1) 6． ······································································· （1 分） 即 2 x 2x 8 0 ． ·················································································· （1 分） 得 x 4 0或 x 2 0． ·········································································· （2 分） 解得 x 4 或 x 2 ． ·············································································· （1 分） 所以，原方程的根是 x1 4，x2 2． ·························································· （1 分） 1 21．（1） s2 20t ； 0.452 ； ········································································ （2 分） （2）3；10；·························································································· （2 分） （3）乙；6． ··························································································· （2 分） 22．（1）作图略． ····················································································· （2 分） （2）解：过点 E 作 EH BC 于点 H ． ························································ （1 分） 由尺规作图可得： DB DE DF ，得 BF 2BD 10 . A ∵ DB DE ，∴∠B ∠BED . E 同理 ∠BFE ∠FED . ∵∠B ∠BED ∠BFE ∠FED 180 ， ∴ 2(∠BED ∠FED) 180 . B D H F C 即∠BEF 90 . ····································· ... ...