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請問一下 u''+2*P*Q*u'+(Q^2)*u= - (e^(-at))sinwt 這題當P<1時 u的齊性解與特解 謝謝 -- ※ 發信站: 批踢踢實業坊(ptt.cc) ◆ From: 140.116.75.13
lookyya:應該會是P<1 y=e^(mx) 用b^2-4*a*c<0 10/24 14:04
lookyya:根會是複數 會是 yc= C1*Cos?Wt + C2*Sin?Wt 10/24 14:07
lookyya:yp 硬下去算就好 10/24 14:09
lookyya:更正 m=a(+-)bi yc= C1*(e^at)*Cos(bt)+C2*(e^at)*Sin(bt) 10/25 11:38
lookyya:w=b時 yp=A*x*Cos(wt)+B*x*Sin(wt) 找 10/25 11:42
lookyya:w=b時 yp=A*x*(e^at)*Cos(wt)+B*x*(e^at)*Sin(wt) 找 10/25 11:44
lookyya:w=\=b時 yp=A*(e^at)*Cos(wt)+B*(e^at)*Sin(wt) 找 10/25 11:45
lookyya:A和B求出就是答案 不擅BBS回答請見諒 10/25 11:46