設(shè)函數(shù)

在

及
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時取得極值.
(1)求
、b的值;
(2)若對于任意的

,都有

成立,求
c的取值范圍.
試題分析:解:(1)

,
因為函數(shù)

在

及
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取得極值,則有

,

.
即

解得

,

.
(2)由(1)可知,

,

.
當(dāng)

時,

;
當(dāng)

時,

;
當(dāng)

時,

.
所以,當(dāng)

時,

取得極大值

,又

,

.
則當(dāng)

時,

的最大值為

.
因為對于任意的

,有

恒成立,
所以

,
解得

或

,
因此

的取值范圍為

.
點評:主要是根據(jù)導(dǎo)數(shù)的符號于函數(shù)單調(diào)性的關(guān)系來得到函數(shù)的極值和最值,得到求解,屬于基礎(chǔ)題。
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