complex i

Discussion in 'Math' started by stupid, Dec 12, 2010.

  1. stupid

    Thread Starter Active Member

    Oct 18, 2009
    81
    0
    hi,
    whats the solution to
    \sqrt[3]{2+i11}?

    help is greatly appreciated.
    thank u.
     
  2. Georacer

    Moderator

    Nov 25, 2009
    5,142
    1,266
    Is that a homework question? Care to post the whole of the question?
     
  3. stupid

    Thread Starter Active Member

    Oct 18, 2009
    81
    0
    ±hi georacer,
    its not homework but m doing self study on basic maths related to signals & systems.

    the eq is ^{x^3-15x-4=0}
    then x=\sqrt[3]{2+\sqrt{-121}}+\sqrt[3]{2-\sqrt{-121}}

    (2±i)^{3}=2±i11=2±\sqrt{-121}}

    x=(2+i)+(2-i)=4

    i m wondering what method to arrive at the last stage.

    hope someone shed lite on that.
    thanks
     
    Last edited: Dec 12, 2010
  4. Georacer

    Moderator

    Nov 25, 2009
    5,142
    1,266
    stupid likes this.
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