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设x>0,y>0,且xy-(x+y)=1,则( ) A.x+y≤2+2 B.x+...
设x>0,y>0,且xy-(x+y)=1,则( )
A.x+y≤2
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+2
B.x+y≥2
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+2
C.x+y≤(
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+1)
2D.x+y≥(
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+1)
2
考点分析:
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设函数f(x)=Asin(ωx+φ)(A≠0,ω>0,)
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对称,它的周期是π,则( )
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![manfen5.com 满分网](http://img.manfen5.com/res/GZSX/web/STSource/20131024183128917458383/SYS201310241831289174583013_ST/2.png)
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上是减函数
C.f(x)的一个对称中心是
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已知向量
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={cosα,sinα},
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A.
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