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设a>0且a≠1,则“函数f(x)=logax在(0,+∞)上为增函数”是“函数...
设a>0且a≠1,则“函数f(x)=logax在(0,+∞)上为增函数”是“函数g(x)=x3-a在(0,+∞)上为减函数”的( )
A.充分不必要条件
B.必要不充分条件
C.充分且必要条件
D.既不充分也不必要条件
考点分析:
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2=2px的焦点与椭圆
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的右焦点重合,则p的值为( )
A.-2
B.2
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常数a>0,焦点在x轴上的椭圆x
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A.3
B.
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C.
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D.
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下列命题中是真命题的是( )
A.∃x
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≤0
B.∀x∈R(2,+∞),2
x>x
2C.若x>1,则x
2>
D.若x<y,则x
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2
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双曲线
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的焦距为( )
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D.4
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设函数
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,其中a>0,曲线y=f(x)在点P(0,f(0))处的切线方程为y=1.
(Ⅰ)确定b,c的值;
(Ⅱ)设曲线y=f(x)在点(x
1,f(x
1))及(x
2,f(x
2))处的切线都过点(0,2).证明:当x
1≠x
2时,f′(x
1)≠f′(x
2);
(Ⅲ)若过点(0,2)可作曲线y=f(x)的三条不同切线,求a的取值范围.
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