(本題滿分15分)本題文科做.
已知二次函數(shù)
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的二次項系數(shù)為
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,且不等式
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的解集為
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.
(1)若方程
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有兩個相等的實數(shù)根, 求

的解析式;
(2)若
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的最大值為正數(shù),求

的取值范圍.
第一問利用
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∴
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所以
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然后由方程
因為方程②有兩個相等的根,所以
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得到。
第二問,由
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及
由
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解得
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解:(1)
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∴
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所以
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…………………………2分
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①
由方程
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② ……………………4分
因為方程②有兩個相等的根,所以
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,
即
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………………………6分
由于
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代入①得

的解析式為
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……………………………8分
(若本題沒有舍去“
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”第一小問得6分)
(2)由
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及
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……………………………12分
由
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解得
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故當(dāng)
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的最大值為正數(shù)時,實數(shù)
a的取值范圍是

…15分
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已知函數(shù)

.
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圖象上的不同兩點

,如果在函數(shù)

圖象上存在點

(其中

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
處的切線
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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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
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
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
,(其中

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
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