2014年全国初中数学竞赛试题答案 .pdfVIP

2014年咸宁市初中数学竞赛决赛

九年级试题参考答案

一、选择题

1．D2．B3．B4．D5．A

二、填空题

10517

6．7．8．39．10．526或526

37736

三、解答题

11．解：（1）由已知可得AOx，OBx.

12

∵xx3m，xx4m0，∴m0.··········································3分

1212

2

∵CO2m，(OAOB)12CO1，y

2

∴(xx)122m1，

12

2

即(xx)4xx24m1.·····························································6分

1212

O

21

整理，得9m8m10，

1AOBx

解得m1，m.Q

129CM

∵m0，∴m1.P

1

13

2

∴抛物线的解析式为yxx2.·············································10·分

（第11题答图）

22

（2）存在这样的点P，使得APB为锐角.··········································11·分

13

2

xx20，得x1，x4.

2212

A(1,0)B(4,0)C(0,2)

∴、，而.