Absolute Value

Problem Solving — algebra and arithmetic (GMAT Focus Edition)
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by Ian Stewart » Tue Apr 07, 2009 7:05 pm
Since x^2 is never negative, x^2 = |x^2| = |x|^2. For each of the inequalities above, you can ignore the absolute value signs. So, for example, if |x|^2 < 1, that just means that -1 < x < 1.
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