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Math Help - How to find square root of imaginary number? Test Monday.

  1. #1
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    How to find square root of imaginary number? Test Monday.

    So under the square root number is a negative 8. Should be 2*sqr root of 2. How to they get there? Where does imaginary symbol go usually? Any video links,sites, diagrams will be helpful plz.
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  2. #2
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    Re: How to find square root of imaginary number? Test Monday.

    Hey Melcarthus.

    The simplest answer is to use the polar form of a complex number and use the rules of exponentiation.

    Complex number - Wikipedia, the free encyclopedia
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  3. #3
    Senior Member Educated's Avatar
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    Re: How to find square root of imaginary number? Test Monday.

    This is one of the first things you should have learnt when studying imaginary numbers...

    \sqrt{-8} = \sqrt{8} \cdot \sqrt{-1} = \sqrt{8}i = 2 \sqrt{2}i

    The i is not under the square root.

    The title is also quite misleading. You are trying to find the square root of a negative number, not the square root of an imaginary number. It's more complicated when you are trying to find the square root of an imaginary number.
    Last edited by Educated; February 22nd 2013 at 04:14 PM.
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  4. #4
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    Re: How to find square root of imaginary number? Test Monday.

    I got it after morning practice.
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    Re: How to find square root of imaginary number? Test Monday.

    Quote Originally Posted by Melcarthus View Post
    So under the square root number is a negative 8. Should be 2*sqr root of 2. How to they get there? Where does imaginary symbol go usually? Any video links,sites, diagrams will be helpful plz.

    (\sqrt{8}i)^2=(2\sqrt2i)^2=-8

    Now that is a simple answer.
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