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Math Help - some tricky eqn

  1. #1
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    some tricky eqn

    so, my assignment is due in 4 hours, but i can't solve this eqn

    dy/dt = -y^4 + 2y^3 + 63y^2

    my TA told me to isolate the equation for -y^2, and that's what i got:

    dy/dt = -y^2(y^2 - 2y - 63)
    = -y^2(y - 9)(y + 7)

    i have no clue to solve it...
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  2. #2
    Rhymes with Orange Chris L T521's Avatar
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    Chicago, IL
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    Quote Originally Posted by boxmailman View Post
    so, my assignment is due in 4 hours, but i can't solve this eqn

    dy/dt = -y^4 + 2y^3 + 63y^2

    my TA told me to isolate the equation for -y^2, and that's what i got:

    dy/dt = -y^2(y^2 - 2y - 63)
    = -y^2(y - 9)(y + 7)

    i have no clue to solve it...
    Separate the variables to get -\int\frac{\,dy}{y^2(y-9)(y+7)}=\int\,dx

    Apply the method of partial fractions to integrate the LHS of the equation.

    Can you take it from here?
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  3. #3
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    thnx a lot, that was really helpful!!!
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