已知函數(shù)
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.
(Ⅰ)若
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,使得不等式
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成立,求
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的取值范圍;
(Ⅱ)求使得等式
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成立的
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的取值范圍.
(Ⅰ)
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;(Ⅱ)
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.
試題分析:(Ⅰ)根據(jù)
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=
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求出
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的最小值,從而求得得不等式
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成立的
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的取值范圍.
(Ⅱ)由
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=
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,可知當(dāng)且僅當(dāng)
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時有
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,從而
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成立.解不等式
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由此求得
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的取值范圍.
試題解析:(Ⅰ)由
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=
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3分
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使得不等式
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成立的
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的取值范圍是
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5分
(Ⅱ)由
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
=
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7分
所以
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,當(dāng)且僅當(dāng)
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時取等 9分
所以
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的取值范圍是
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10分
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