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$\begingroup$

$\frac{1}{\frac{1}{a}+\frac{1}{b}}+\frac{1}{\frac{1}{c}+\frac{1}{d}} \leq \frac{1}{\frac{1}{a+b}+\frac{1}{c+d}}$

I think it has something to do with Harmonic mean, but can't fighre it out.

  • 0
    Are a,b,c,d $> 0$?2012-11-14
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    I don't see the linear algebra here.2012-11-14
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    it doesn't say that a,b,c,d >0, but let's pressume they are. can you solve it if they are?2012-11-14

2 Answers 2