满分5 >
初中数学试题 >
(2002•朝阳区)用换元法解方程-8x2+12=0,下列换元过程中,原方程变形...
(2002•朝阳区)用换元法解方程
![manfen5.com 满分网](http://img.manfen5.com/res/CZSX/web/STSource/20131019105453850943599/SYS201310191054538509435009_ST/0.png)
-8x
2+12=0,下列换元过程中,原方程变形不正确的是( )
A.设
![manfen5.com 满分网](http://img.manfen5.com/res/CZSX/web/STSource/20131019105453850943599/SYS201310191054538509435009_ST/1.png)
,则
![manfen5.com 满分网](http://img.manfen5.com/res/CZSX/web/STSource/20131019105453850943599/SYS201310191054538509435009_ST/2.png)
B.设2x
2-3=y,则
![manfen5.com 满分网](http://img.manfen5.com/res/CZSX/web/STSource/20131019105453850943599/SYS201310191054538509435009_ST/3.png)
C.设8x
2-12=y,则
![manfen5.com 满分网](http://img.manfen5.com/res/CZSX/web/STSource/20131019105453850943599/SYS201310191054538509435009_ST/4.png)
D.设
![manfen5.com 满分网](http://img.manfen5.com/res/CZSX/web/STSource/20131019105453850943599/SYS201310191054538509435009_ST/5.png)
,则y-
![manfen5.com 满分网](http://img.manfen5.com/res/CZSX/web/STSource/20131019105453850943599/SYS201310191054538509435009_ST/6.png)
考点分析:
相关试题推荐
(2002•朝阳区)从2002年5月9日开始的一周内,北京某地区每天的最高气温依次是(单位:℃):30,31,34,33,32,31,33.那么这7个数据的平均数和中位数分别是( )
A.32和32
B.32和33
C.33和32
D.33和33
查看答案
(2002•朝阳区)在△ABC中,∠C=90°,∠A=30°,sinA+cosB的值等于( )
A.
![manfen5.com 满分网](http://img.manfen5.com/res/CZSX/web/STSource/20131019105453850943599/SYS201310191054538509435007_ST/0.png)
B.1
C.
![manfen5.com 满分网](http://img.manfen5.com/res/CZSX/web/STSource/20131019105453850943599/SYS201310191054538509435007_ST/1.png)
D.
查看答案
(2002•朝阳区)下列各式从左到右变形正确的是( )
A.
![manfen5.com 满分网](http://img.manfen5.com/res/CZSX/web/STSource/20131019105453850943599/SYS201310191054538509435006_ST/0.png)
+
![manfen5.com 满分网](http://img.manfen5.com/res/CZSX/web/STSource/20131019105453850943599/SYS201310191054538509435006_ST/1.png)
=3(x+1)+2y
B.
![manfen5.com 满分网](http://img.manfen5.com/res/CZSX/web/STSource/20131019105453850943599/SYS201310191054538509435006_ST/2.png)
=
![manfen5.com 满分网](http://img.manfen5.com/res/CZSX/web/STSource/20131019105453850943599/SYS201310191054538509435006_ST/3.png)
C.
![manfen5.com 满分网](http://img.manfen5.com/res/CZSX/web/STSource/20131019105453850943599/SYS201310191054538509435006_ST/4.png)
=
![manfen5.com 满分网](http://img.manfen5.com/res/CZSX/web/STSource/20131019105453850943599/SYS201310191054538509435006_ST/5.png)
D.
![manfen5.com 满分网](http://img.manfen5.com/res/CZSX/web/STSource/20131019105453850943599/SYS201310191054538509435006_ST/6.png)
=
查看答案
(2002•朝阳区)顺次连接三角形三边的中点,所构成的三角形与原三角形对应高的比是( )
A.1:4
B.1:3
C.1:2
D.1:1
查看答案
(2002•朝阳区)正n边形的一个内角为120°,那么n为( )
A.5
B.6
C.7
D.8
查看答案