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#1 2013-11-11 09:32:55

anonimnystefy
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From: The Foundation
Registered: 2011-05-23
Posts: 14,843

Function sign

Has anyone got an idea about getting the sign of this function:


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#2 2013-11-12 04:48:30

gAr
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Registered: 2011-01-09
Posts: 3,462

Re: Function sign

Hi,

It's negative for x>1, but what was the question?


"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."

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#3 2013-11-12 15:19:51

anonimnystefy
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From: The Foundation
Registered: 2011-05-23
Posts: 14,843

Re: Function sign

Hi gAr

I managed to get that result as well, but in a very complicated way, which is surprising, since it is a book problem.

The function comes from analysing a different function

for monotonity.


“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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#4 2013-11-12 17:16:47

gAr
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Registered: 2011-01-09
Posts: 3,462

Re: Function sign

Hi anonimnystefy,

Okay, I only plotted it, nothing else.


"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."

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#5 2013-11-13 00:21:25

anonimnystefy
Real Member
From: The Foundation
Registered: 2011-05-23
Posts: 14,843

Re: Function sign

So, do you have any ideas?


“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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#6 2013-11-13 06:06:07

gAr
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Registered: 2011-01-09
Posts: 3,462

Re: Function sign

We can see that x^2-1 increases faster than x log x, for x>1.


"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."

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#7 2013-11-13 09:07:44

anonimnystefy
Real Member
From: The Foundation
Registered: 2011-05-23
Posts: 14,843

Re: Function sign

But, what about the -x^2log(x) term?


“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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#8 2013-11-13 17:59:49

gAr
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Registered: 2011-01-09
Posts: 3,462

Re: Function sign

I was talking about the equation in #3


"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."

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#9 2013-11-14 09:20:26

anonimnystefy
Real Member
From: The Foundation
Registered: 2011-05-23
Posts: 14,843

Re: Function sign

Ah, I see. But, how exactly do I show that it is decreasing.


“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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#10 2013-11-15 05:57:10

gAr
Member
Registered: 2011-01-09
Posts: 3,462

Re: Function sign

Well, I don't know, inequalities is in my todo list!


"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."

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