作者baitlunas (小贝)
看板trans_math
标题一题极限的证明
时间Thu Nov 13 21:49:18 2008
定义:f(x)=x,x rational
0,x irrational
(a)Show that f is not diff on 0.
g(x)=x平,x rational
0 ,x irrational
(b)Show that g is diff at 0 and give g'(0)
据说正确解法要用delta,epsilon法
--
※ 发信站: 批踢踢实业坊(ptt.cc)
◆ From: 140.114.216.112
1F：→ Qmmm:(a)f'(x属於Q) =1≠f'(x不属於Q)=0 140.112.128.93 11/13 22:58
2F：→ Qmmm:(b)f'(x属於Q)=f'(x不属於Q)=>2x=0, 只有在 140.112.128.93 11/13 22:59
3F：→ Qmmm: x=0处可微分。 140.112.128.93 11/13 22:59
4F：→ yhliu:楼上写法很可能得 0 分! 218.170.31.177 11/14 10:21
5F：→ yhliu:也不见得需用到ε-δ的讨论; 218.170.31.177 11/14 10:22
6F：→ yhliu:用 "可微" 或 "导数" 的定义即可. 218.170.31.177 11/14 10:23