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Math Help - Need help in finding all complex solutions

  1. #1
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    Need help in finding all complex solutions

    I tried working it out but I didn't get the right answer... Btw the correct answer is "B" which is highlighted.... What did I do wrong?
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    Re: Need help in finding all complex solutions

    Quote Originally Posted by asilvester635 View Post
    I tried working it out but I didn't get the right answer... Btw the correct answer is "B" which is highlighted.... What did I do wrong?
    You have the right idea, but you factored wrong. (x^2)^2 - 8(x^2) - (3^2) \neq ( (x^2) - 3 )^2. How do you factor y^2 - 8y - 9?

    -Dan
    Last edited by topsquark; November 23rd 2013 at 05:22 PM.
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    Re: Need help in finding all complex solutions

    x^4-8x^2-9=(x^2-9)(x^2+1).
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    Re: Need help in finding all complex solutions

    Quote Originally Posted by Plato View Post
    x^4-8x^2-9=(x^2-9)(x^2+1).
    Which factorises further :P
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    Re: Need help in finding all complex solutions

    Quote Originally Posted by Prove It View Post
    Which factorises further :P
    But why do that? The roots are perfectly obvious from that product.
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    Re: Need help in finding all complex solutions

    Quote Originally Posted by Plato View Post
    But why do that? The roots are perfectly obvious from that product.
    To you and me perhaps, not to everyone though...
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