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## #1 2012-09-24 19:59:31

hammana
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### 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

## #2 2012-09-24 22:52:05

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

Hi hammana

Have you heard of the AM-GM inequality?

The limit operator is just an excuse for doing something you know you can't.
“It's the subject that nobody knows anything about that we can all talk about!” ― Richard Feynman
“Taking a new step, uttering a new word, is what people fear most.” ― Fyodor Dostoyevsky, Crime and Punishment

## #3 2012-09-25 02:35:30

bobbym

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### 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.