[]甘肃省兰州市2019届九年级5月模拟考试数学试题（扫描版）

九年级数学模拟答案第 1页（共 7页） 2019年兰州市九年级数学模拟考试 参考答案及评分参考 本答案仅供参考，阅卷时会制定具体的评分细则和评分标准。 一、选择题：本大题共 12 小题，每小题 4 分，共 48 分. 题号 1 2 3 4 5 6 7 8 9 10 11 12 答案 A D D B C B D C C A B B 二、填空题：本大题共 4小题，每小题 4分，共 16分. 13. 2x(x－2)2 14. 9 16 15. 2022 16. (8，3)或( 5 2 ，0) 三、解答题：本大题共 12小题，共 86分.解答时写出必要的文字说明、证明过程或演算步 骤. 17．(5分) 解：(－1)2019＋ 3 8－( 1 3 )－2＋ 2 sin45° ＝－1＋2－9＋ 2 × 2 2 ·················································································· 1，2，3，4分 ＝－7．································································································································· 5分 18．(5分) 解：原式＝x2－9＋4x2－4x＋1－4x2＋4x········································································ 1，2，3分 ＝x2－8，·························································································································4分 当 x 7＝ 时，原式＝7－8＝－1．······················································································· 5分 19．(5分) 解： 3 4 2 3 2 3 x x x     ＋ ＜ ① ＋ ＋ ＞ ② 由①得 x＜1．······················································································································ 2分 由②得 x＞0．······················································································································ 4分 ∴不等式组的解集为 0＜x＜1．························································································5分 20．(6分) 证明：∵DE∥AB， ∴∠EDA＝∠CAB．············································································································1分 在△ABC和△DAE中 CAB EDA AB DA B DAE       ＝ ＝ ＝ ，········································································4分 九年级数学模拟答案第 2页（共 7页） ∴△ABC≌△DAE(ASA)．······························································································· 5分 ∴BC＝AE．························································································································· 6分 21．(7分) 解：（1）样本容量是 1000，··················································································