小芳king
幼苗
共回答了17个问题采纳率:88.2% 举报
已知数列
![](https://img.yulucn.com/upload/9/a6/9a6d9627a38df6aad638bc4c6b49a9c9_thumb.jpg)
中,
![](https://img.yulucn.com/upload/f/4e/f4e8cdf8af4f4034ade0c6212152b65e_thumb.jpg)
,且有
![](https://img.yulucn.com/upload/4/49/449319ebcf2fd5d329b1e842d4bfe6d9_thumb.jpg)
.
(1)写出
![](https://img.yulucn.com/upload/8/f9/8f96d2200b26800d134e76b8232a8cb0_thumb.jpg)
所有可能的值;
(2)是否存在一个数列
![](https://img.yulucn.com/upload/9/a6/9a6d9627a38df6aad638bc4c6b49a9c9_thumb.jpg)
满足:对于任意正整数
![](https://img.yulucn.com/upload/a/4b/a4bf2384ffa915da0c4531c87a0c0c0d_thumb.jpg)
,都有
![](https://img.yulucn.com/upload/1/29/1296562ecf2e4e1f5ba10fdb4dd40c5d_thumb.jpg)
成立?若有,请写出这个数列的前6项,若没有,说明理由;
(3)求
![](https://img.yulucn.com/upload/6/50/6507960550642cd93fb6d581b34d8ab7_thumb.jpg)
的最小值.
(1)
![](https://img.yulucn.com/upload/3/22/3222ecda787ee349e5c42e7a1507e070_thumb.jpg)
(2) 存在,
![](https://img.yulucn.com/upload/8/27/827e910625dff185ff4774c48f95fee5_thumb.jpg)
(或者取
![](https://img.yulucn.com/upload/e/2d/e2d7bcb2bdcc53b215821bc46fbf8cb8_thumb.jpg)
)(3)1
试题分析:
(1)根据
![](https://img.yulucn.com/upload/4/49/449319ebcf2fd5d329b1e842d4bfe6d9_thumb.jpg)
,计算
![](https://img.yulucn.com/upload/a/ff/aff7fd99994b0181b8ee88e2fa0ea645_thumb.jpg)
的值有两个,根据
![](https://img.yulucn.com/upload/a/ff/aff7fd99994b0181b8ee88e2fa0ea645_thumb.jpg)
的两个值,再计算
![](https://img.yulucn.com/upload/6/1c/61caca5f52e0fbfed210f569213b72e6_thumb.jpg)
即可.
(2)罗列出所有的可能数列,从中观察是否有满足
![](https://img.yulucn.com/upload/1/29/1296562ecf2e4e1f5ba10fdb4dd40c5d_thumb.jpg)
(即
![](https://img.yulucn.com/upload/c/2f/c2f620c5cef6e5785e61750c3bc04661_thumb.jpg)
)的即可.
(3)根据
![](https://img.yulucn.com/upload/4/49/449319ebcf2fd5d329b1e842d4bfe6d9_thumb.jpg)
特点可知
![](https://img.yulucn.com/upload/9/19/9190b19107dc0545ae58654170bea0aa_thumb.jpg)
,且所有的奇数项都为奇数,偶数项为偶数, 因此
![](https://img.yulucn.com/upload/9/5e/95efab6f88646446ff43609657308f2f_thumb.jpg)
中一定有5个奇数,5个偶数,所以
![](https://img.yulucn.com/upload/1/90/1905eb8da607e141d53b76885b30ad7b_thumb.jpg)
一定是奇数,所以
![](https://img.yulucn.com/upload/8/7a/87a6c9031e4a2261e395de2a2204f139_thumb.jpg)
.
(1) 根据题意
![](https://img.yulucn.com/upload/f/4e/f4e8cdf8af4f4034ade0c6212152b65e_thumb.jpg)
,且有
![](https://img.yulucn.com/upload/4/49/449319ebcf2fd5d329b1e842d4bfe6d9_thumb.jpg)
,所以可得
![](https://img.yulucn.com/upload/e/44/e4428919a0cbe2d77eb7d13453f0f180_thumb.jpg)
,带入
![](https://img.yulucn.com/upload/4/49/449319ebcf2fd5d329b1e842d4bfe6d9_thumb.jpg)
,可得
所以
![](https://img.yulucn.com/upload/9/cf/9cf1473e7fa62277fce96a4fd6aa6eb2_thumb.jpg)
可能取的值
(2) 存在
这个数列的前6项可以为
![](https://img.yulucn.com/upload/8/27/827e910625dff185ff4774c48f95fee5_thumb.jpg)
(或者取
![](https://img.yulucn.com/upload/e/2d/e2d7bcb2bdcc53b215821bc46fbf8cb8_thumb.jpg)
)
(3)
![](https://img.yulucn.com/upload/1/90/1905eb8da607e141d53b76885b30ad7b_thumb.jpg)
的最小值为1
因为
![](https://img.yulucn.com/upload/6/d0/6d07cd54dc2d396eda7bf6508edcc234_thumb.jpg)
,所以
![](https://img.yulucn.com/upload/9/19/9190b19107dc0545ae58654170bea0aa_thumb.jpg)
,且所有的奇数项都为奇数,偶数项为偶数
因此
![](https://img.yulucn.com/upload/9/5e/95efab6f88646446ff43609657308f2f_thumb.jpg)
中一定有5个奇数,5个偶数,
所以
![](https://img.yulucn.com/upload/1/90/1905eb8da607e141d53b76885b30ad7b_thumb.jpg)
一定是奇数,所以
令这10项分别为
(或者为
![](https://img.yulucn.com/upload/7/53/75387258c37e441205b1df09973f4f40_thumb.jpg)
,或者为
![](https://img.yulucn.com/upload/6/fb/6fb27457ac8fddd330c0f985aa941aea_thumb.jpg)
)
则有
![](https://img.yulucn.com/upload/6/7c/67c93bad8ca67efb286ed7dcdf7afc09_thumb.jpg)
.
1年前
3