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命题A:(x-1)2<9,命题B:(x+2)•(x+a)<0;若A是B的充分不必...
命题A:(x-1)2<9,命题B:(x+2)•(x+a)<0;若A是B的充分不必要条件,则a的取值范围是( )
A.(-∞,-4)
B.[4,+∞)
C.(4,+∞)
D.(-∞,-4]
考点分析:
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设n∈N
*,f(n)=1+
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+
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+…+
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,计算知f(2)=
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,f(4)>2,f(8)>
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,f(16)>3,f(32)>
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,由此猜测( )
A.f(2n)>
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B.f(n
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C.f(2
n)≥
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D.以上都不对
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③“p∨q”为真是“¬p”为假的必要不充分条件;
④“¬p”为真是“p∧q”为假的必要不充分条件.
A.①②
B.①③
C.②④
D.③④
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下列说法错误的是( )
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