已知复数z=1-2i,那么
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=( )
A.
![manfen5.com 满分网](http://img.manfen5.com/res/GZSX/web/STSource/20131024183525281069828/SYS201310241835252810698001_ST/1.png)
B.
![manfen5.com 满分网](http://img.manfen5.com/res/GZSX/web/STSource/20131024183525281069828/SYS201310241835252810698001_ST/2.png)
C.
![manfen5.com 满分网](http://img.manfen5.com/res/GZSX/web/STSource/20131024183525281069828/SYS201310241835252810698001_ST/3.png)
D.
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考点分析:
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已知集合M={x|-3<x≤5},N={x|-5<x<5},则M∩N=( )
A.{x|-5<x<5}
B.{x|-3<x<5}
C.{x|-5<x≤5}
D.{x|-3<x≤5}
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设a
1,a
2,…,a
20是首项为1,公比为2的等比数列.对于满足0≤k≤19的整数k,数列
![manfen5.com 满分网](http://img.manfen5.com/res/GZSX/web/STSource/20131024183525281067878/SYS201310241835252810678019_ST/0.png)
![manfen5.com 满分网](http://img.manfen5.com/res/GZSX/web/STSource/20131024183525281067878/SYS201310241835252810678019_ST/1.png)
确定.记
![manfen5.com 满分网](http://img.manfen5.com/res/GZSX/web/STSource/20131024183525281067878/SYS201310241835252810678019_ST/2.png)
.
(I)当k=1时,求M的值;
(II)求M的最小值及相应的k的值.
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设a>0,函数
![manfen5.com 满分网](http://img.manfen5.com/res/GZSX/web/STSource/20131024183525281067878/SYS201310241835252810678018_ST/0.png)
.
(I)若f(x)在区间(0,1]上是增函数,求a的取值范围;
(Ⅱ)求f(x)在区间(0,1]上的最大值.
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设直线l:y=k(x+1)与椭圆x
2+3y
2=a
2(a>0)相交于A、B两个不同的点,与x轴相交于点C,记O为坐标原点.
(Ⅰ)证明:
![manfen5.com 满分网](http://img.manfen5.com/res/GZSX/web/STSource/20131024183525281067878/SYS201310241835252810678017_ST/0.png)
;
(Ⅱ)若
![manfen5.com 满分网](http://img.manfen5.com/res/GZSX/web/STSource/20131024183525281067878/SYS201310241835252810678017_ST/1.png)
,△OAB的面积取得最大值时椭圆方程.
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如图,正三棱柱ABC-A
1B
1C
1中,D是BC的中点,AA
1=AB=1.
(I)求证:A
1C∥平面AB
1D;
(II)求二面角B-AB
1-D的大小;
(III)求点c到平面AB
1D的距离.
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