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## #1 2013-08-24 04:19:42

Al-Allo
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### Little question

Hi, : http://imageshack.us/photo/my-images/827/34f2.png/

I'm just wondering, I know that a rational expression can't be divided by 0, but what does he man by "identically" ???I feel like there's something I'm missing... any help please ! Thank you !

## #2 2013-08-24 04:32:29

anonimnystefy
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### Re: Little question

x-x is identically equal to 0 because it is 0 for any value of x.

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 2013-08-24 04:50:18

bob bundy
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### Re: Little question

hi Al-Allo

In your example you could drop the word altogether and have "The only restriction is that the divisor must not be equal to zero"  and it still makes perfect sense.  I've been trying to find situations where just using 'equals' is not appropriate ...  without much success I have to say.

Some mathematicians use 'identically equal' instead of 'equivalent' and it is often used for identities eg.

and also eg.

If you google the two word phrase you'll get more examples.

Meanwhile, here's a challenge for members:

Find an example where you cannot leave out the word 'identically' without changing the meaning.

Bob

You cannot teach a man anything;  you can only help him find it within himself..........Galileo Galilei

Al-Allo
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Ok, thank you.

## #5 2013-08-24 05:07:56

anonimnystefy
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### Re: Little question

Hi Bob

In math or in general?

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

## #6 2013-08-24 05:21:34

bob bundy
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### Re: Little question

hi Stefy,

I'm be interested in either / both.

Bob

You cannot teach a man anything;  you can only help him find it within himself..........Galileo Galilei

## #7 2013-08-24 06:48:30

anonimnystefy
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### Re: Little question

In math such an example, I think, doesn't exist. But, either way, the question is a bit ambiguous.

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

## #8 2013-08-24 16:55:29

bob bundy
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### Re: Little question

I suppose what I'm really saying is the word 'identically'  is redundant in the sentence.  So then I wonder, is it always redundant.  So far, I think, yes.  So I'm curious about whether a case exists where it isn't.

I prefer concepts to words in maths.  There are often many ways of expressing the same idea.  Sometimes posters get hung up on the words when I think they should be concentrating on the concepts.  The same is true of the symbols used.  eg. the recent Boolean algebra question.  There are at least three different notations there, but the underlying maths is consistent throughout.

Bob

You cannot teach a man anything;  you can only help him find it within himself..........Galileo Galilei