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Math Help - plz Help me

  1. #1
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    plz Help me

    what is y?
    y^(5)+2y=0
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  2. #2
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    Quote Originally Posted by iloveyou7 View Post
    what is y?
    y^(5)+2y=0

    I'm not sure I understand. Is this the equation:

     y^5 + 2y = 0 ?

    You've posted this in the differential equation section, and this isn't a differential equation. Did you mean:

     \frac{d^5y}{dx^5} + 2y = 0 ?
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  3. #3
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    Quote Originally Posted by Mush View Post
    I'm not sure I understand. Is this the equation:

     y^5 + 2y = 0 ?

    You've posted this in the differential equation section, and this isn't a differential equation. Did you mean:

     \frac{d^5y}{dx^5} + 2y = 0 ?
    yes, i mean
     \frac{d^5y}{dx^5} + 2y = 0
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  4. #4
    Grand Panjandrum
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    Quote Originally Posted by iloveyou7 View Post
    what is y?
    y^{(5)}+2y=0
    Use a trial solution e^{\lambda t} , this gives you a charateristic equation:

    \lambda^5+2=0

    so \lambda=(-2)^{1/5} that is the general solution is:

    y(t)=Ae^{\lambda_1t}+Be^{\lambda_2t}+Ce^{\lambda_3  t}+De^{\lambda_4t}+Ee^{\lambda_5t}

    where the \lambda_i 's are the fith roots of -2

    CB
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