将下列问题的解答过程补充完整.
依次计算数列
,
,
,
,…的前四项的值,由此猜测
的有限项的表达式,并用数学归纳法加以证明.
解:计算
,
,
① ,
② ,
由此猜想
③ .(*)
下面用数学归纳法证明这一猜想.
(i)当
时,左边
,右边
,所以等式成立.
(ⅱ)假设当
时,等式成立,即
④ .
那么,当
时,
⑤
⑥
⑦ .
等式也成立.
根据(i)和(ⅱ)可以断定,(*)式对任何
都成立.
依次计算数列
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/bdaa19de263700a15fcf213d64a8cd57.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d6424c9c0ce88c2701bb3b83067a051d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/df93fdc8ca17ee10a2d6b54e54213acd.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4e77db166dbdada6e51bd5e603a0e409.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f8406b3952927dd9017ab411dcac57b8.png)
解:计算
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/876d453473dd136199f4fd4653f00a47.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/8a4f19a71132d1b0c1b94e8ed4a71d84.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6d1447bca977671d5ce032975edb0878.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a27e4ece094c7799ca69c4742b573aec.png)
由此猜想
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5bb7dc2d8e081b24e0ac29e2f04b4c35.png)
下面用数学归纳法证明这一猜想.
(i)当
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c87b351f16728b0023fd63678f8103c7.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f90bae886c8ab958aa4c693bf8e0627d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f90bae886c8ab958aa4c693bf8e0627d.png)
(ⅱ)假设当
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7bd127e6c509dce7558952d89d436148.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ce436c13abda6f1c8cc297d4f707dbf2.png)
那么,当
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/63ba21f3d0cfc86d40e2e06446623ce0.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/53bf6680c197e995a4a9c13e8b363eb7.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/90ea95e79eac5ee4d3a76c4112e1f077.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6706fe00b4e231e62d9ecbec567d526b.png)
等式也成立.
根据(i)和(ⅱ)可以断定,(*)式对任何
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/36b98ef143f8159f3a7dafa1fd2f2370.png)
更新时间:2020-05-30 07:32:21
|
【知识点】 数学归纳法证明数列问题解读
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