已知
分别是与x轴,y轴正方向相同的单位向量,
,对任意正整数n,
.
(1)若
,求a的值;
(2)求向量
;
(3)记
,若不等式
恒成立,求实数a的取值范围.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e0d0f5edd2ad69fa56e7782b85bba717.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a0fd4ce43685ca97ee2816f6312a5232.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/cd2808f6a2f014dcc6833a6f23f704f3.png)
(1)若
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ef973011d4954d469d4fb1b006feb2e1.png)
(2)求向量
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/cae8824ce99db6c44633cc81b2c4257d.png)
(3)记
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ed2938bdc6bcb2e3cd8d6510263d8dda.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b79672ffe0b0627b99daa3d4f5984d4b.png)
更新时间:2022-10-08 12:54:56
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适中
(0.65)
解题方法
【推荐1】已知
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(1)求
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4b72a569ce967cbd5ec671f3719c2c0d.png)
(2)求
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f9daab6e6fe7d8d4381014b786761d09.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/cae8824ce99db6c44633cc81b2c4257d.png)
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