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## #1 2011-07-18 10:33:52

Thanh Vān
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### Inequality In [1;3]

Let a,b,c be real numbers in [1;3]. prove that

Last edited by Thanh Vān (2011-07-18 10:34:34)

## #2 2011-07-18 23:56:17

anonimnystefy
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### Re: Inequality In [1;3]

hi Thanh Vān

i tried to find the maximum value of the left part which is for a=b=c=3 and equals (3√2)/2, and the minimum value of the right part which is for a=b=c=1 and equals (9√2)/2 ,so for any other possible values for a,b and c the inequality will always be true.i think this is not the prefered method for solving this kind of problems but it is the only one i could come up with.

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 2011-07-20 00:30:31

Thanh Vān
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### Re: Inequality In [1;3]

Hi anonimnystefy.
Look my inequality, you can see Maximun of left Inequality is when a=b=c=3 and minimum right inequality is same as yourself.
But it is very easy to talk so.
I thinks it is a problem very very nice, and we can solve it by basic 's inequality.
Maybe it is CS and AM-GM.

## #4 2011-07-22 04:44:29

gAr
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### Re: Inequality In [1;3]

Hi Thanh Vān,

"Believe nothing, no matter where you read it, or who said it, no matter if I have said it, unless it agrees with your own reason and your own common sense"  - Buddha?

"Data! Data! Data!" he cried impatiently. "I can't make bricks without clay."

## #5 2011-07-22 21:14:20

Thanh Vān
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### Re: Inequality In [1;3]

Hi gAr, I don't see you completed solution for my inequality (=left your proven). Please see again your post. Thanks.

## #6 2011-07-22 21:25:12

gAr
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### Re: Inequality In [1;3]

Hi Thanh Vān,

Yes, I saw that after posting.
I'll try again sometime later.

"Believe nothing, no matter where you read it, or who said it, no matter if I have said it, unless it agrees with your own reason and your own common sense"  - Buddha?

"Data! Data! Data!" he cried impatiently. "I can't make bricks without clay."