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Math Help - question about inequalities with negative numbers and square roots

  1. #1
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    Question question about inequalities with negative numbers and square roots

    let's say you have an inequality such as this:

    -1< -2x2 < 1 and it reduces to 1/square root of 2 > x > -1/square root of 2

    I understand why the inequalities can flip around but I forgot why you don't end with an imaginary number due to taking
    the square root of a negative number.
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  2. #2
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    Re: question about inequalities with negative numbers and square roots

    Quote Originally Posted by matnov View Post
    let's say you have an inequality such as this:
    -1< -2x2 < 1 and it reduces to 1/square root of 2 > x > -1/square root of 2
    Note that -1<-2x^2<1 can be written as |-2x^2|<1 so |x|<\frac{\sqrt{2}}{2}.
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    Re: question about inequalities with negative numbers and square roots

    thank you, I think I understand. great site by the way - but can anyone refer me to some free software that will let me post mathematical notation on this forum? thanks
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    Re: question about inequalities with negative numbers and square roots

    Quote Originally Posted by matnov View Post
    thank you, I think I understand. great site by the way - but can anyone refer me to some free software that will let me post mathematical notation on this forum? thanks
    It is LaTeX. Go to the LaTeX subforum.
    Last edited by Plato; January 10th 2013 at 04:01 PM.
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