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xyz inequality (Posted on 2015-07-24) Difficulty: 2 of 5

  
If x, y, and z are nonnegative real numbers,
then prove that

   x2 + xy2 + xyz2 ≥ 4xyz - 4
  

  Submitted by Bractals    
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Solution: (Hide)

  
   x2 + xy2 + xyz2 ≥ 4xyz - 4

      if and only if

   (x - 2)2 + x(y - 2)2 + xy(z - 2)2 ≥ 0

QED


Note: the inequality is true even if z is any
          real number instead of nonnegative.
  

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  Subject Author Date
solutionDaniel2015-07-24 08:45:54
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