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Math Help - Differential Equations

  1. #1
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    Differential Equations

    a) Write down the general solution to the differential equation dy/dx + 5y = 0.

    b) Use a suitable trial function to find one simple particular solution of dy/dx + 5y = 3e^(-9x)

    c) Find the solution of dy/dx + 5y = 3e^(-9x) that satisfies y(0) = -27/4.

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  2. #2
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    Quote Originally Posted by mr_motivator View Post
    a) Write down the general solution to the differential equation dy/dx + 5y = 0.
    What, you can't do that ? o.O

    \frac{dy}{dx}=-5y
    \frac{dy}{y}=-5 ~dx
    The LHS integrates to \ln(y), the RHS integrates to -5x+c

    b) Use a suitable trial function to find one simple particular solution of dy/dx + 5y = 3e^(-9x)
    Try something like k e^{-9x}...

    c) Find the solution of dy/dx + 5y = 3e^(-9x) that satisfies y(0) = -27/4.

    Cheers...
    Use the above.
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