贵州省安顺市关岭县2020-2021学年九年级上学期期末考试数学试题（图片版）

安顺市关岭县2020—2021学年 第一学期基础教育教学质量监测卷 九年级数学 参考答案及评分标准 一、选择题(本大题共10小题，每小题3分，共30分) 1.D 2.C 3.A 4.B 5.C 6.A 7.D 8.B 9.C 10.B 二、填空题(本大题共5小题，每小题4分，共20分) 11. 12. 8 13. x1＝6，x2＝2 14. 2 15. 三、解答题(本大题共10小题，共100分) 16.解：(1)移项，得4x28x＝3． 方程两边都除以4，得x22x． 方程两边都加1，得x22x+11． 配方，得(x1)2＝． 开平方，得x1＝． ∴x＝1， ∴x11，x21． ·································································4分 (2)移项，得(x+3)25(x+3)＝0． ∴(x+3)(x+35)＝0， ∴(x+3)(x2)＝0， ∴x1＝3，x2＝2． ············································································8分 17.解：(1)如图所示，△A1B1C1即为所求． ·······················································3分 (2)如图所示，△A2B2C2即为所求． ·····························································5分 A2(4，2)，B2(2，1)，C2(3，5)． ·······················································8分 18.(1)证明：∵CD⊥AB，∴， ∴∠AGD＝∠ADC． ················································································2分 ∵四边形ADCG是O的内接四边形， ∴∠FGC＝∠ADC， ∴∠FGC＝∠AGD． ···············································································4分 (2)解：如图，连接OD． ∵CD⊥AB，CD＝4， ∴DE＝CE＝2． ····················································································6分 在Rt△DOE中，∵OD2＝OE2+DE2， ∴OD2＝(OD1)2+22，解得OD＝， ························································8分 ∴AE＝2ODBE＝51＝4， ∴AD． ··················································10分 19.解：(1)设每年绿化面积的平均增长率为x． 由题意，得1200(1+x)2＝1587． ····························································3分 解得x1＝0.15， x2＝2.15(不合题意，舍去)． ········································5分 所以每年绿化面积的平均增长率为15%． ·····················································6分 (2) 1587×(1+15%)＝1825.05(万平方米)． 所以2021年的绿化面积是1825.05万平方米． ·············································10分 20.解：(1)(4，5) ··················································································2分 (2)设抛物线的函数解析式为y＝ax2． 将点B(4，5)代入y＝ax2，得5＝a×42，解得a． ∴抛物线的函数解析式为yx2． ····················································6分 (3)将x＝2代入yx2，得y． ∵2，而1.8＜2， ∴当水面离拱顶1.8 m时，木船不能通过这