作者Honor1984 (希望愿望成真)
看板trans_math
标题Re: [积分] 91中兴第一题~
时间Sun Jul 6 21:06:53 2008
※ 引述《chat543 (小ㄐ)》之铭言：
: Find a function f and a constant c such that
: x
: ∫ tf(t)dt = sinx - xcosx -1/2x^2 , for all x.
: c
x=c sinc-c*cosc - 0.5 c^2 = 0
=> c = 0
xf(x) = cosx - cosx + xsinx - x
=>f(x) = [xsinx - x]/x
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※ 发信站: 批踢踢实业坊(ptt.cc)
◆ From: 122.124.106.124
1F：推 chat543:感谢^^~125.229.192.196 07/06 21:18