设函数
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(1)若

证明:

。
(2)若不等式
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对于
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及
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恒成立,求实数

的取值范围。
令

则



在

上是增函数。
故

即

。
(2)原不等式等价于

。
令

则

。
令

得

列表如下(略)

当

时,


。
令

则

解得

或

。
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
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
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
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
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
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
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
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
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
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
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
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
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
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