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平面内原有k条直线,它们的交点个数记f(k),则增加一条直线ι后,它们的交点个数...
平面内原有k条直线,它们的交点个数记f(k),则增加一条直线ι后,它们的交点个数最多为( )
A.f(k)+1
B.f(k)+k
C.f(k)+k+1
D.k•f(k)
考点分析:
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3,a
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n=( )
A.
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B.
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C.
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D.
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若函数f(x)满足f(x+1)=f(x-1),且当x∈[-1,1]时,f(x)=x
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若向量
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,则
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的最小值为( )
A.
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B.
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C.
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D.2
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![manfen5.com 满分网](http://img.manfen5.com/res/GZSX/web/STSource/20131101230927970823386/SYS201311012309279708233005_ST/0.png)
=( )
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若a,b是两个互相垂直的非零向量,则在以下给出的式子“①
![manfen5.com 满分网](http://img.manfen5.com/res/GZSX/web/STSource/20131101230927970823386/SYS201311012309279708233004_ST/0.png)
=0;②
![manfen5.com 满分网](http://img.manfen5.com/res/GZSX/web/STSource/20131101230927970823386/SYS201311012309279708233004_ST/1.png)
+
![manfen5.com 满分网](http://img.manfen5.com/res/GZSX/web/STSource/20131101230927970823386/SYS201311012309279708233004_ST/2.png)
=
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-
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;③|
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+
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|=|
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-
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|;④
2+
2=(
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+
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)
2;⑤(
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)•(
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)=0”中正确的有( )
A.1个
B.2个
C.3个
D.4个
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