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:

  1. 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)

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  2. 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

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  3. 哦~我會了
    謝謝老師

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