2011北京中考二模数学知识点分类汇编：计算题(2)

2

5． ····················································································································· 5分

14．解不等式组

2x 4 5(x 2),

并求它的正整数解.

3(x 1) x 3,

2x 4 5(x 2),

并求它的正整数解.

3(x 1) x 3,

14．解不等式组

解：

2x 4 5(x 2),

3(x 1) x 3,

由①，得x≥－2． ······································································································· 1分 由②，得x＜3． ········································································································· 2分 不等式组的解集在数轴上表示如下：

························································· 3分 所以原不等式组的解集为－2≤x＜3． ········································································ 4分 所以原不等式组的正整数解为1，2． ······································································· 5分

(平谷)

1．－5的绝对值是 A

C． 5

D．

A．5 B．－5

1 5

6．在一次射击测试中，甲、乙、丙、丁四名运动员射击的平均环数均相同，而方差分别为8.7，6.5，9.1，7.7，则这四人中，射击成绩最稳定的是 B A．甲

B．乙

C．丙

D．丁

11．一个圆锥的母线长为3cm，侧面展开图是圆心角为120o的扇形， 则圆锥的侧面积是

3π

o

cm2．

（ 4) 13．计算：tan30

13．解：

tan30o （ 4)0 6

32 1= 3 ……….…………………………………………………….4分

= 1 …………………………………..………………………………………………5分

(燕山)

2．在直角坐标系中，点M（1，-2011）关于原点的对称点坐标是 C

A.（1，2011） B.（-1，-2011） C.（-1，2011） D.（-2011，1） 9. 函数y =

x

的自变量取值范围是__ x ≠-3______. x 3

3

____ 2

10.已知x= - 4是一元二次方程mx2+5x=6m的一个根，则另一个根是__

11.学校本学期安排初二学生参加军训，李小明同学5次实弹射击的成绩（单位：环）如下：9，4，10，8，9. 这组数据的极差是____6___(环)；方差是__4.4______（环2）

13．把多项式9mx4-6mx2+m在实数范围内因式分解.

13.原式= m（9x4-6 x2+1） ………………………………………1分 = m (3 x2-1)2 ………………………………………………3分 = m (x+1)2 (3x-1) 2 . ………………………………………………5分

3x 1

4,

14．解不等式组 并写出不等式组的非负整数解. 2

4x 1）； x 2 （

14.解①得 x<3； ……………………………………………1分

解②得 x -2 . ………………………………………………2分

∴ 不等式组的解集是-2 x<3. ……………………………………………3分