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Basic Propertiesof numbers

  1. Aug 15, 2008 #1
    1. The problem statement, all variables and given/known data
    Find all number x for which 5-x^2 < 8

    2. Relevant equations

    3. The attempt at a solution
    Adding -5 from both sides we get -x^2 < 3
    x^2 > -3
    then it is impossible that x > sqrt -3...
    Any idea how to solve this step bystep
  2. jcsd
  3. Aug 15, 2008 #2
    If you think about, you're asking when is five minus a positive number less than eight, and the answer to that is always, [tex](-\infty, \infty)[/tex].
  4. Aug 15, 2008 #3


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    Staff Emeritus
    Science Advisor

    Not only is it possible for x2 to be greater than -3, since x2 is always non-negative it is always true!
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