2009学年第一学期九年级数学答案
2009学年第一学期九年级数学期中素质检测卷
参考答案与评分标准
一、选择题(本题有10小题,每题4分,共40分)
1.B
2.D 3.B 4.B 5.B 6.C 7.D 8.B 9.B 10.D
二、填空题(本题有6小题,每题5分,共30分)
11.Y=2(x+1)2+3
12.-1 13.5
14.8 15.400
16.(-2,5)或(1,-4) 三、解答题(本题有8小题,第17~20题每题8分,第21题10分,第22、23题每题12分,
17. (1) 画图正确 ··········································································· 4分
(2)∠BAC=1160 ……………………………………………………………………8分
18.(1)反比例函数的解析式为y=x
3 ······························································· 3分 E 点的坐标 是(4,
43 ) ···································································· 5分 (2)F (2,2
3 ) ············································································· 7分 所以 点F 在此反比例函数的图象上………………………………………8分
19.如图设 矩形的一边为x 米,则对应的矩形面积为y 平方米…………………………1分 由题意得,y=-4x 2+40x
=-4(x-5)2+100………………………………………………………………6分 所以x=5时,矩形鸡圈的面积最大,为100平方米。…………………………………8分
20.(1)正确的是 ③ ④ ··············································································· 2分
证明正确 ······················································································· 8分
21.(1) 材料加热时y 与x 的函数关系式y=9x+15……………………………………3分 停止加热进行操作时y 与x 的函数关系式为y=x
300……………………………………6分 (2)共经历了20分钟……………………………………………………………………10分
22.(1)6x 4x 2
1y 2-+-=……………………………………………………………3分 (2)(2,0),(6,0)……………………………………………………………………6分
(3) 略……………………………………………………………………………………9分
(4)2<x <6………………………………………………………………………………12分
23.(1)证明正确…………………………………………………………………………6分
(2)BC 的长为32……………………………………………………………………12分
24.(1)1412+-
=x y ……………………………………………………………………4分 (2)相等.
设E(m ,m),代入14
12+-=x y , 得(不符,舍)或222m ,222--=+-=m ………………………………7分
所以EG=2-(222+-)=224-,OE=2×(222+-)=224-
所以EG=OE …………………………………………………………………… 9分
(3)设H(x ,1412+-x ),则由勾股定理得OH=14
12+x ,…………………11分 JH=2 - (1412+-x )=14
12+x ,故OH=JH,…………………………………12分 于是可得△OHI ≌△JKC .………………………………………………………14分