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Math Help - Quadratic formula for complex roots

  1. #1
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    Quadratic formula for complex roots

    This is a bit embarrassing. I am using the quadratic formula to obtain two complex roots and for the life of me I can not get the answer posted on the solution sheet. Could someone please take a look and see if I am wrong or, perhaps, the answer sheet is? Thanks much, Frostking

    (3 - x) multiplied by -- (1 - x) + 8 = 0

    - x^2 + 4x + 5 = 0

    When I use the quadratic I get 2 +/- - i = 2 +/- i

    I am suppose to get 1 +/- 2i

    I know I am going to say how stupid can I be but......I do not know where I am going wrong!!!
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  2. #2
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    Quote Originally Posted by Frostking View Post
    This is a bit embarrassing. I am using the quadratic formula to obtain two complex roots and for the life of me I can not get the answer posted on the solution sheet. Could someone please take a look and see if I am wrong or, perhaps, the answer sheet is? Thanks much, Frostking

    (3 - x) multiplied by -- (1 - x) + 8 = 0

    - x^2 + 4x + 5 = 0

    When I use the quadratic I get 2 +/- - i = 2 +/- i

    I am suppose to get 1 +/- 2i

    I know I am going to say how stupid can I be but......I do not know where I am going wrong!!!
    Working backwards, if the answer is x = 1\pm2i then the question must have been "((3 – x) multiplied by –(1 + x)) + 8 = 0". Check that you copied the question correctly.
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