1 . 已知函数
,其中a,b,
.
(1)当
时,求函数
的单调区间;
(2)若对任意
,都有
恒成立,求实数
的最小值.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/11976693acdf39ca341f1a2e115ba075.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c4166972dec0aa3e8694a44eeb941a08.png)
(1)当
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/48adb8a59b5c02fad5eada1b35171cf3.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/942c2141d01bde6b48210c56a17fc75e.png)
(2)若对任意
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0f7dbb416ec1ff1984a724a4f48bf692.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c47545bd5310d9c5c8de5f64a2a6e2e1.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a5aa200de40134d6c0c865a9bc7ecb3b.png)
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2 . 设
,数列{xn}满足
.若1≤x7≤2,则x8的取值范围为____________ .
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a6dc6b2701de8807efd7cc22e1f21af7.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/68513f125e6766a039eab3ab01cce834.png)
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3 . 设
满足
数列
是公差为
,首项
的等差数列; 数列
是公比为
首项
的等比数列,求证:
.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e4935544664f86edc57a0c3410fcf897.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5217df154813a81ad37c406027e9f667.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/76c6099506bd60534ed57a71e3678b31.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/affd21d3fc4f76dcc7fffa227541df28.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5f6cc218c568cc9d08e620696d1f61f0.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b6e8e67f649bb2e18fc02d6118ff4e2a.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/decb5e8546e79397586cbbdf0fc2e085.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6c1f5a2d53d857943074a092006e110d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/50dedd2d9712979cae558023a3ae94b9.png)
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