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reyes
Lv 4
reyes asked in Science & MathematicsMathematics · 10 years ago

Differential equation help.?

y'=y+e^x

I have no idea how to solve this and I'm stuck here.

dy/dx = y + e^x

dy/dx = ce^x +e^x

dy = (ce^x + e^x)dx

⌠dy = ⌠(ce^x + e^x) dx

y= ?

The answer should be y= ce^x +(e^x)x

I don't know where the last x comes from.

Thank you for your help.

1 Answer

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  • 10 years ago
    Favorite Answer

    I do not understand the method you are using to solve this.

    Solve this differential equation by using an integrating factor:

    y' = y + ℮˟

    dy / dx = y + ℮˟

    dy / dx - y = ℮˟

    dy / dx + P(x)y = f(x)

    P(x) = -1

    f(x) = ℮˟

    I(x) = ℮^[∫ P(x) dx]

    I(x) = ℮^(∫ -1 dx)

    I(x) = ℮ˉ˟

    I(x) = 1 / ℮˟

    I(x)y = ∫ I(x)f(x) dx

    y / ℮˟ = ∫ 1 dx

    y / ℮˟ = x + C

    y = (x + C)℮˟

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