作者yuyumagic424 (五月飞雪)
看板trans_math
标题Re: [极限]
时间Tue Aug 26 23:04:58 2008
※ 引述《Qmmm (Q蛆蛆)》之铭言：
: (1)极限存在时，问r应为多少
: (2)极限值=?
3 5 7
x 2x 17x
tanx = x + --- + ----- + ------ + ...
3 15 315
3 5 7
(sinx) 2(sinx) 17(sinx)
tan(sinx) = sinx + ------ + --------- + ------------- + ....
3 15 315
3 5 7 3 5 7
x x x 1 x x x 3
= (x - --- + --- - --- + ... ) + -- (x - --- + --- - --- + ... )
3! 5! 7! 3 3! 5! 7!
2 5 17 7
+ --- (懒得打 囧) + --- (囧...) + ......
15 315
1 3 1 5 3 7
= x + --- x - --- x - --- x + ....
6 40 560
3 5 7
tanx tanx tanx
而 sin(tanx) = tanx - ---- + ---- - ----
3! 5! 7!
= .....
1 3 1 5 79 7
= x + --- x - --- x - --- x + ....
6 40 840
=>
3 79 7
- --- + --- x + ...........
560 840
lim --------------------------------
x→0 r
x
故 r 为 7
3 79
极限值等於 - --- + ---
560 840
--
※ 发信站: 批踢踢实业坊(ptt.cc)
◆ From: 140.112.243.42
1F：→ Qmmm:这跟1/30的答案差蛮多的?? 119.14.151.98 08/27 00:21
2F：→ yuyumagic424:刚忘了 r<7也是可以 极限值就是0 140.112.243.42 08/27 00:54
3F：→ yuyumagic424:r=7时 极限值就是分子 x^7的系数 140.112.243.42 08/27 00:55
4F：→ yuyumagic424:想知道就自己做一遍吧@@ 140.112.243.42 08/27 00:55
※ 编辑: yuyumagic424 来自: 140.112.243.42 (08/27 01:01)