Thread: Problem 28
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Old June 26th, 2007, 05:53 AM
mathisfun1 mathisfun1 is offline
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According to AM-GM, \frac{x^2+y^2}{2} \ge xy. Do the same for the other pairs of variables and add to get the desired inequality.


Credit must be given where credit is due -- I picked up this trick from the AoPS book Vol 2.