2008-04-07

線代解微分方程


請問綠色框框是怎麼算出來的呢??
麻煩各位看看
謝謝了

3 則留言:

黃子嘉 提到...

x2' = -4x2 - 4e^(-2t)
特微方程式a + 4 = 0
=> a = -4
齊次解x2(h) = ce^(-4t)
令特解x2(p) = d e^(-2t)代入原式
-2d e^(-2t)
= -4(d e^(-2t)) - 4e^(-2t)
=> -2d = -4d - 4
=> d = -2
=> x2(p) = -2 e^(-2t)
則x2 = x2(h) + x2(p)
= c e^(-4t) - 2e^(-2t)

黃子嘉 提到...

x1' = -2x1 - e^(-2t)
特徵方程式a + 2 = 0
=> a = -2
=> x1(h) = c e^(-2t)
令x1(p) = d t e^(-2t)代入原式
d e^(-2t) - 2d t e^(-2t)
= -2d t e^(-2t) - 2e^(-2t)
=> d - 2dt = -2dt - 2
=> d = -2
=> x1(p) = -2te^(-2t)
=> x1 = x1(h) + x1(p)
= c e^(-2t) - 2te^(-2t)

這些觀念會用到微分方程

Unknown 提到...

哦~我會了
謝謝老師