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Simple differential equation problem I am having trouble with?

Solve the separable linear fi rst order DE: dy/dx -4xy =0

using both the method of separation of variables and using an integrating factor.

I can solve it using the separation of variables technique, I'm just having trouble with the integration factor method.

4 Answers

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  • 8 years ago

    dy/dx -4xy =0

    dy=4xydx

    dy/y=4xdx

    by integrating both sides

    ln y = 4 x^2/2 +C

    ln y= 2x^2+C

    y= e^(2x^2+C)

  • Anonymous
    8 years ago

    dy/dx - 4xy = 0

    Compare with : dy/dx + Py = Q

    P = -4x Q=0

    I = e^(Pdx) = e^(-2x^2)

    Solution is:

    yI = (QI)dx = 0dx = c

    y * e^(-2x^2) = c

    Taking log on both sides

    lny -2x^2 = lnc

    lny = 2x^2 + k

    where k is a constant

  • Anonymous
    8 years ago

    dy/dx=4xy

    dy/y=4xdx

    ln y=2x^2

    y=(e^2x^2)+c

  • ?
    Lv 7
    8 years ago

    y' - 4xy = 0

    µ = e^(∫-4x dx)

    µ = e^(-2x^2)

    e^(-2x^2)y' - 4xye^(-2x^2) = 0

    ∫ d/dx(ye^(-2x^2))dx = ∫0dx

    ye^(-2x^2) = 0 + c

    y = ce^(2x^2)

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