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Math Help - Find Polynomial given zeros

  1. #1
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    Find Polynomial given zeros


    I get this far, and then i get stuck..i dont know what to do...when I multiply by (X + 8i), i keep getting the wrong answer..could someone please help me? Thank you
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  2. #2
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    If you want all real coefficients, then the complex roots must occur in conjugate pairs.
    So use {-3,4,8i,-8i} four roots give four factors.
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  3. #3
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    Now I get
    x^2 - x - 12 (x^2 - 64i^2)
    Now do I multiply those together?
    Last edited by aikenfan; September 28th 2007 at 01:42 PM.
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  4. #4
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     \left( {x^2  - x - 12} \right)\left( {x^2  + 64} \right) =  \left( {x^2 } \right)\left( {x^2 } \right) + \left( {x^2 } \right)\left( {64} \right) + \left( { - x} \right)\left( {x^2 } \right) + \left( { - x} \right)\left( {64} \right) + \left( { - 12} \right)\left( {x^2 } \right) + \left( { - 12} \right)\left( {64} \right)<br />
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  5. #5
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    x^4 - x^3 + 52x^2 - 768
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  6. #6
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    Quote Originally Posted by aikenfan View Post
    x^4 - x^3 + 52x^2 - 768
    You missed a term.
    x^4 - x^3 + 52x^2 -64x - 768
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  7. #7
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    Thank you for all of your help
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