作者Ilove17 (小卡)
看板Grad-ProbAsk
标题[理工] [工数]-二阶ODE
时间Fri Oct 23 21:25:53 2009
请问一下
u''+2*P*Q*u'+(Q^2)*u= - (e^(-at))sinwt
这题当P<1时
u的齐性解与特解
谢谢
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1F：→ lookyya:应该会是P<1 y=e^(mx) 用b^2-4*a*c<0 10/24 14:04
2F：→ lookyya:根会是复数 会是 yc= C1*Cos?Wt + C2*Sin?Wt 10/24 14:07
3F：→ lookyya:yp 硬下去算就好 10/24 14:09
4F：→ lookyya:更正 m=a(+-)bi yc= C1*(e^at)*Cos(bt)+C2*(e^at)*Sin(bt) 10/25 11:38
5F：→ lookyya:w=b时 yp=A*x*Cos(wt)+B*x*Sin(wt) 找 10/25 11:42
6F：→ lookyya:w=b时 yp=A*x*(e^at)*Cos(wt)+B*x*(e^at)*Sin(wt) 找 10/25 11:44
7F：→ lookyya:w=\=b时 yp=A*(e^at)*Cos(wt)+B*(e^at)*Sin(wt) 找 10/25 11:45
8F：→ lookyya:A和B求出就是答案 不擅BBS回答请见谅 10/25 11:46