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#1 2012-09-23 21:59:31

hammana
Member
Registered: 2012-03-02
Posts: 48

inequation a/b+b/c+c/d+d/a>=4

If a, b, c, d are 4 positive numbers, show that
a/b+b/c+c/d+d/a>=4

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#2 2012-09-24 00:52:05

anonimnystefy
Real Member
From: The Foundation
Registered: 2011-05-23
Posts: 15,400

Re: inequation a/b+b/c+c/d+d/a>=4

Hi hammana

Have you heard of the AM-GM inequality?


“Here lies the reader who will never open this book. He is forever dead.

“Taking a new step, uttering a new word, is what people fear most.” ― Fyodor Dostoyevsky, Crime and Punishment

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#3 2012-09-24 04:35:30

bobbym
Administrator
From: Bumpkinland
Registered: 2009-04-12
Posts: 84,654

Re: inequation a/b+b/c+c/d+d/a>=4

Hi;

Have you left out some constraint on this problem?


In mathematics, you don't understand things. You just get used to them.
I have the result, but I do not yet know how to get it.
All physicists, and a good many quite respectable mathematicians are contemptuous about proof.

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