满分5 >
初中数学试题 >
(2002•昆明)下列结论正确的是( ) ①方程=-2没有实数根; ②解方程()...
(2002•昆明)下列结论正确的是( )
①方程
![manfen5.com 满分网](http://img.manfen5.com/res/CZSX/web/STSource/20131021232516037950644/SYS201310212325160379506002_ST/0.png)
=-2没有实数根;
②解方程(
![manfen5.com 满分网](http://img.manfen5.com/res/CZSX/web/STSource/20131021232516037950644/SYS201310212325160379506002_ST/1.png)
)
2-2(
![manfen5.com 满分网](http://img.manfen5.com/res/CZSX/web/STSource/20131021232516037950644/SYS201310212325160379506002_ST/2.png)
)=0时,若设y=
![manfen5.com 满分网](http://img.manfen5.com/res/CZSX/web/STSource/20131021232516037950644/SYS201310212325160379506002_ST/3.png)
,则原方程变形为y
2-2y-3=0;
③存在这样的两个实数a、b,使得
![manfen5.com 满分网](http://img.manfen5.com/res/CZSX/web/STSource/20131021232516037950644/SYS201310212325160379506002_ST/4.png)
;
④当a≠0时,关于x的方程ax=b总有实数根.
A.①②③
B.①②④
C.①③④
D.②③④
考点分析:
相关试题推荐
(2002•青海)下列方程中,有正实数根的是( )
A.2x+1=0
B.x
2+3x+4=0
C.x+
![manfen5.com 满分网](http://img.manfen5.com/res/CZSX/web/STSource/20131021232516037950644/SYS201310212325160379506001_ST/0.png)
=0
D.
查看答案
(2002•无锡)下列方程中,有实数根的是( )
A.x
2-x+1=0
B.x
2+x-1=0
C.x+
![manfen5.com 满分网](http://img.manfen5.com/res/CZSX/web/STSource/20131021232516037950644/SYS201310212325160379506000_ST/0.png)
=1+
![manfen5.com 满分网](http://img.manfen5.com/res/CZSX/web/STSource/20131021232516037950644/SYS201310212325160379506000_ST/1.png)
D.
![manfen5.com 满分网](http://img.manfen5.com/res/CZSX/web/STSource/20131021232516037950644/SYS201310212325160379506000_ST/2.png)
+2=0
查看答案
(2002•东城区)在Rt△ABC中,∠C=90°,斜边c=5,两直角边的长a,b是关于x的一元二次方程x
2-mx+2m-2=0的两个根,求Rt△ABC中较小锐角的正弦值.
查看答案
(2002•朝阳区)已知:如图,△ABC内接于⊙O,AD是⊙O的直径,点E、F分别在AB、AC的延长线上,EF交⊙O于点M、N,交AD于点H,H是OD的中点,
![manfen5.com 满分网](http://img.manfen5.com/res/CZSX/web/STSource/20131021232516037865666/SYS201310212325160378656026_ST/0.png)
,EH-HF=2.设∠ACB=a,tana=
![manfen5.com 满分网](http://img.manfen5.com/res/CZSX/web/STSource/20131021232516037865666/SYS201310212325160378656026_ST/1.png)
,EH和HF是方程x
2-(k+2)x+4k=0的两个实数根.
(1)求EF和HF的长;
(2)求BC的长.
查看答案
(2002•烟台)如图,已知△ABC的面积为5,点M在AB边上移动(点M与点A、B不重合),MN∥BC,MN交AC于点N,连接BN.设
![manfen5.com 满分网](http://img.manfen5.com/res/CZSX/web/STSource/20131021232516037865666/SYS201310212325160378656025_ST/0.png)
=x,S
△MBN=y.
(1)求y关于x的函数关系式,并写出自变量x的取值范围;
(2)点E、F分别是边AB,AC的中点,设△MBN与△EBF的公共部分的面积为S,试用含x的代数式表示S;
(3)当第(2)问中的S=
![manfen5.com 满分网](http://img.manfen5.com/res/CZSX/web/STSource/20131021232516037865666/SYS201310212325160378656025_ST/1.png)
时,试确定x的值.(不必写出解题过程)
查看答案