請問這個點做呢.....::
圖片參考：http://img84.imageshack.us/img84/5746/memlaplace.png
Laplace Transform II
2010-12-06 7:40 pm
回答 (1)
2010-12-06 10:56 pm
✔ 最佳答案
QUESTION1 L(cos2t)=s/(s^2+4)
L(tcos2t)
=-d/dt [s/(s^2+4)]
=-[(s^2+4)-s(2s)]/(s^2+4)^2
=(s^2-4)/(s^2+4)^2
QUESTION 2
L(sin3t)=3/(s^2+9)
L(tsin3t)
=-d/dt [3/(s^2+9)]
=-[-3(2s)]/(s^2+9)^2
=6s/(s^2+9)^2
L(t^2sin3t)
=-d/dt [6s/(s^2+9)^2]
=-[6(s^2+9)^2-12s(s^2+9)(2s)]/(s^2+9)^4
=-[6(s^2+9)-24s^2)]/(s^2+9)^3
=(18s^2-54)/(s^2+9)^3
收錄日期: 2021-04-26 14:01:13
原文連結 [永久失效]:
https://hk.answers.yahoo.com/question/index?qid=20101206000051KK00397