2023年江苏省无锡市天一实验学校九年级中考数学模拟试题

初三数学练习参考答案

一、选择题（本大题共10小题，每小题3分，共30分，在每小题所给出的四个选项中，只有一项是正确的，请用2B铅笔把答题卡上相应的选项标号涂黑）

1-5.  ADCDA    6-10.  CBDBD

二、填空题（本大题共8小题，每小题3分，共24分，其中第18题第一空1分，第二空2分．不需写出解答过程，只需把答案直接填写在答题卡上相应的位置）

11.  x(x+1)( x-1)

12.  x≠2

13.  2

14.  略

15.  50（1- x）（1-2 x）

16.  20°

17.  90°

18.  ；2或

三、解答题（本大题共10小题，共96分，请在答题卡指定区城内作答，解答时应写出文字说明、证明过程或演算步骤）

19.  （1）           （2）a-1

20.  （1）x1=3，x2=-1      （2）

21. （1）证明：在△ABC和△ACD中
AB = AG
∠BAE = ∠CAD
AE = AD
∴△ABC≌△ACD (SAS)·························5分

(2)由（1）得：△ABC≌△ACD

  ∴∠ABE = ∠ACD
∵AB= AC
∴ ∠ABC = ∠ACB
∴. ∠ABC - ∠ABE =∠ACD - ∠ACD.
即∠CBF=∠BCF
∴ BF = CF ·············································5分

22.

（1）不可能   随机······················································4分

（2）········································································6分

23.

（1）8········································································2分

10········································································1分

0.25······································································2分

（2）略；····································································2分

（3）720 ·····································································2分

85％······································································1分

24.

（1）连接OD，∵ 0B=OD,
∴∠B=∠ODB
∵AE=DE
∴∠EDA=∠A
∵∠ACB=90°
∴∠B+∠A =90°

              ∴∠ODB+∠EDA=90°

              ∴∠ODE=90°

              ∴DO⊥ED

              ∴是⊙O的切线··································5分

（2）AE=··································································5分

25.

（1）·······································································5分

（2）···········································································5分

26.

（1）足球100元/个，跳绳20元/根。································5分

（2）购进45个足球，15根跳绳最省钱。···························5分

27.

（1）y=x²-2x-3·······························································3分

（2）P(-2,5) ·································································3分

（3）P(-,)································································4分

28.

（1）······································································2分

（2）DF=AE·····························································3分

（3）定值， ····························································3分

（4）DF＇=AE＇·················································2分