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4-ball B^4

  1. Nov 11, 2008 #1
    1. The problem statement, all variables and given/known data

    What is the x-simple description of a 4-ball = { ||x|| [tex]\leq[/tex] r }

    2. Relevant equations

    It's a 4-ball, so isn't the equation x[tex]^{2}[/tex] + y^2 +z^2 +w^2 ?

    3. The attempt at a solution
    For my limits, I got x is between [tex]\pm[/tex] [tex]\sqrt{1-z^2}[/tex] and y is between -1 and 1, and z is between [tex]\pm[/tex] [tex]\sqrt{1-x^2-y^2}[/tex], and w is between [tex]\pm[/tex] [tex]\sqrt{1-x^2-y^2-z^2}[/tex] Is this right? Thanks!
  2. jcsd
  3. Nov 11, 2008 #2
    buuumppp...please help! Any advice is good!
  4. Nov 12, 2008 #3


    Staff: Mentor

    That couldn't possibly be the equation. An equation always states that two expressions have the same value. I see only one expression, and even more to the point, I don't see an equals sign.

    What does x-simple description mean?
    Where did the 1 come from?
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