2021年江苏省南通市通州区中考网上阅卷第一次适应性训练数学试题（扫描版）

数学4开-1 数学4开-2 $ 数学试题参考答案与评分标准 第 1 页（共 4 页） 2021 年中考模拟考试 数学试题参考答案与评分标准 说明：本评分标准每题只给出了一种解法供参考，如果考生的解法与本解答不同，参照本评 分标准给分． 一、选择题（本大题共 10 小题，每小题 3 分，共 30 分） 题号 1 2 3 4 5 6 7 8 9 10 选项 B C A D D C A B A B 二、填空题（本大题共 8 小题，第 11～12 小题每小题 3 分，第 14～18 小题每小题 4 分，共 30 分） 11．2 12．100 13．n(m－2)2 14．30 15． 600 450 50x x   16． 3 8 17．4042 18．4 三、解答题（本大题共 8 小题，共 90 分） 19．（1）（本小题满分 4 分） 解：原式＝2(m2－2m＋1)－(4m2－9) ································································ 2 分 ＝2m2－4m＋2－4m2＋9 ····························································· 3 分 ＝－2m2－4m＋11； ································································· 4 分 19．（2）（本小题满分 6 分） 解：方程两边同时乘以 3(x＋1)得：3x＝2x＋3x＋3； ·········································· 3 分 解得 x＝ 3 2 － ；············································································· 5 分 检验：当 x＝ 3 2 － 时，3(x＋1)≠0， 所以原分式方程的解为 x＝ 3 2 － ······················································· 6 分 20．（本小题满分 10 分） 解：（1）设 l1：y=kx＋b，又 A（－4，0），B（0，8）， ∴ 4 0, 8. k b b      ················································· 2 分 ∴ 2, 8. k b    ························································ 4 分 ∴y=2x＋8． ···················································· 5 分 （2）由题意，得 l2：y=－x， ··········································································· 6 分 ∴ 2 8, . y x y x      解得 8 3 8 3 x y        ， ． ······································································· 8 分 y O x A （第 20 题） B C 数学试题参考答案与评分标准 第 2 页（共 4 页） ∴C（ 8 3  ， 8 3 ）． ·················································································· 9 分 ∴S△AOC＝ 1 8 16 4 2 3 3    ． ······································································ 10 分 21．（本小题满分 8 分） （1）小林，180． ······················································································· 4 分 （2）小美：只调查男生数据，不能代表九年级学生的情况，还应对女生进行调查． 小丽：只调查 10 名同学，样本不容易具有代表性，应适当增大样本容量． ·····