已知

(1)若

,求

的值;
(2)若

在

上是增函數(shù),求實數(shù)

的取值范圍.
解:(1)

; (2)

。
(1)由

得

, 可轉化為sinx=0,所以

.
(2)

在

上是增函數(shù),
令

,在

是增函數(shù),則

在

是增函數(shù)
然后轉化二次函數(shù)區(qū)間定軸動的問題解決.
解:(1) 由

得

即

則

…………4分
(2)

在

上是增函數(shù),
令

,在

是增函數(shù),則

在

是增函數(shù)
①

解得

②

,

在

是增函數(shù),符合
③

解得

綜上得

…………6分
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
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
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
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

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
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