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Math Help - integration using partial fractions

  1. #1
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    integration using partial fractions

    integrate (4y^2 -7y-12)/y(y+2)(y-3)dy.
    A/y + B/(y+2) +C(y-3)
    = A(y+2)(y-3) + B(y-3)y +Cy(y+2) = 4y^2-7Y-12
    A=2 B= 9/5 c=1/5.
    [2ln2 + 9/5ln(4) + (1/5)ln(-1)] -[2ln1 + 9/5ln3 + 1/5ln(-2)]
    i dont know if the this is right because ln of a negative number does not exist. That said, where did I go wrong?
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  2. #2
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    Quote Originally Posted by twilightstr View Post
    integrate (4y^2 -7y-12)/y(y+2)(y-3)dy.
    A/y + B/(y+2) +C(y-3)
    = A(y+2)(y-3) + B(y-3)y +Cy(y+2) = 4y^2-7Y-12
    A=2 B= 9/5 c=1/5.
    [2ln2 + 9/5ln(4) + (1/5)ln(-1)] -[2ln1 + 9/5ln3 + 1/5ln(-2)]
    i dont know if the this is right because ln of a negative number does not exist. That said, where did I go wrong?
    I got A= -2, B= -19, C= 25. Check your arithmetic and/or algebra and see if that fixes it for you.
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