找回密码
 立即注册
搜索
总共850条微博

动态微博

查看: 2393|回复: 1
打印 上一主题 下一主题
收起左侧

math problem 2

[复制链接]
achen 该用户已被删除
跳转到指定楼层
楼主
发表于 2004-12-31 00:16:24 | 只看该作者 回帖奖励 |倒序浏览 |阅读模式
提示: 作者被禁止或删除 内容自动屏蔽
回复

使用道具 举报

0

主题

25

帖子

150

积分

沙发
发表于 2005-1-6 02:46:04 | 只看该作者

回复:math problem 2


for k is greater than .25, any function that is (1): symmetric to the y-axis, ie f(-x)=f(x), and (2): f(x) is continuous for all x between [0,k], and (3): f(0)=f(k) will be continuous for all x.
The resulting function is cyclical, with interval(?) k, k^2+k, ((k^2+k)^2)+k,...
www.ddhw.com

We are given that f(A)=f(A^2+k)=f((A^2+k)^2+k)=...
what if A=(A^2+k)? this implies A=(1+(1-4k)^.5)/2 or (1-(1-4k)^.5)/2, so if k is greater than .25, A will never equal to A^2+k.

However if k is less than or equal to .25, and
(case 1): for all A less than (1+(1-4k)^.5)/2, the sequence, A, A^2+k,((A^2+k)^2+k,... will converge to (1-(1-4k)^.5)/2 since... (I think somehow we prove it if can prove it's monotonic decr/incr and (1-(1-4k)^.5)/2 is the root of A=A^2+k ) This implies that f(x) must be a constant for all x between [0, (1+(1-4k))^.5)/2 since they will all equal to f((1-(1-4k)^.5)/2)www.ddhw.com

(case 2): for all A greater than or equal to (1+(1-4k)^.5)/2, if we trace it backward
ie f(A)=f((A-k)^.5)=f(((A-k)^.5-k)^.5)=...., the sequence A,(A-k)^.5, ((A-k)^.5-k)^.5,... will converge to (1+(1-4k)^.5)/2, (again, I think somehow we prove it.) This implies that f(x) must be a constant for all x greater than or equal to (1+(1-4k)^.5)/2 since they will all equal to f((1+(1-4k)^.5)/2)

from (1) and (2). therefore when k is less than or equal to .25, if f(x) is a continuous function,f(x) = constant for all x.www.ddhw.com

 
回复 支持 反对

使用道具 举报

24小时热帖
    一周热门
      原创摄影
        美食美文
          您需要登录后才可以回帖 登录 | 立即注册

          本版积分规则

          Archiver|手机版|珍珠湾ART

          Powered by Discuz! X3 © 2001-2013 All Rights Reserved