作者Frobenius (i^(-i)= e^(π/2))
看板trans_math
标题Re: [微分] 89年考古题
时间Tue May 15 14:22:08 2007
※ 引述《j19880706 (smallpig)》之铭言：
: 这题我想好久 想不透 请大大帮我解题
: -1 ,
: If f(x)= 2X +cosX then (f ) (1) =
: 这题怎麽算阿
: 感谢大大教我
f(x)= 2X +cosx
f(0)= 0 + cos0 = 1
-1
f (1) = 0
-1 -1 -1
f ( f (x) ) = x = 2f (x) + cos( f (x) )
两边做微分
-1 , -1 -1 ,
1 = 2 ( f (x) ) - sin( f (x) )( f (x) )
-1 , -1
1 = ( f (x) ) ( 2 - sin( f (x) ) )
-1 , 1
( f (x) ) = ---------------------
-1
( 2 - sin( f (x) ) )
-1 , 1 1 1
( f (1) ) = --------------------- = ---------- = ---
-1 2 - sin0 2
( 2 - sin( f (1) ) )
--
※ 发信站: 批踢踢实业坊(ptt.cc)
◆ From: 140.122.225.109