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## #1 2012-10-24 08:01:19

Mpmath
Member
Registered: 2012-10-11
Posts: 216

### Infinity multiplied by infinity

Hy everyone!
What do you think about operations with infinity?
We know that  ∞ : ∞ = indeterminate, but what about ∞ * ∞ ?
The result is ∞ ?
A friend of mine suggest this:
n^3 : n = n^2
so
∞^3 : ∞ = ∞^2
so
∞ : ∞ = ∞^2
which means
∞^2 = indeterminate.
Any feedback is welcome.

Winter is coming.

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## #2 2012-10-24 08:35:36

bobbym
From: Bumpkinland
Registered: 2009-04-12
Posts: 104,714

### Re: Infinity multiplied by infinity

In mathematics, you don't understand things. You just get used to them.
If it ain't broke, fix it until it is.
A number by itself is useful, but it is far more useful to know how accurate or certain that number is.

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## #3 2012-10-24 08:44:36

Mpmath
Member
Registered: 2012-10-11
Posts: 216

### Re: Infinity multiplied by infinity

Hi;
So you suggest that infinity multiplied by infinity equals infinity?

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## #4 2012-10-24 08:46:09

bobbym
From: Bumpkinland
Registered: 2009-04-12
Posts: 104,714

### Re: Infinity multiplied by infinity

Hi;

Yes, I think that ∞ * ∞ = ∞.

In mathematics, you don't understand things. You just get used to them.
If it ain't broke, fix it until it is.
A number by itself is useful, but it is far more useful to know how accurate or certain that number is.

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## #5 2012-10-24 08:59:37

anonimnystefy
Real Member
From: Harlan's World
Registered: 2011-05-23
Posts: 16,015

### Re: Infinity multiplied by infinity

Mpmath wrote:

Hi;
So you suggest that infinity multiplied by infinity equals infinity?

Of course. One is that infinity*infinity=infinity and the second is that multiplication is not an operation that should be applied to infinity.

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
The knowledge of some things as a function of age is a delta function.

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## #6 2012-10-24 09:02:56

Mpmath
Member
Registered: 2012-10-11
Posts: 216

### Re: Infinity multiplied by infinity

And way about n : infinity?

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## #7 2012-10-24 09:08:50

bobbym
From: Bumpkinland
Registered: 2009-04-12
Posts: 104,714

### Re: Infinity multiplied by infinity

Hi;

How do you map n to infinity?

Oh wait, I am sorry this : is a division operator. My browser is reading it wrong. Division is not allowed.

In mathematics, you don't understand things. You just get used to them.
If it ain't broke, fix it until it is.
A number by itself is useful, but it is far more useful to know how accurate or certain that number is.

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## #8 2012-10-24 09:26:43

Mpmath
Member
Registered: 2012-10-11
Posts: 216

### Re: Infinity multiplied by infinity

Sorry, bobbym, n to infinity or n : infinity?

Winter is coming.

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## #9 2012-10-24 09:28:50

bobbym
From: Bumpkinland
Registered: 2009-04-12
Posts: 104,714

### Re: Infinity multiplied by infinity

Hi;

I did not understand your notation. First let's get that right. What are you saying here:

n^3 : n = n^2

I am not following that.

In mathematics, you don't understand things. You just get used to them.
If it ain't broke, fix it until it is.
A number by itself is useful, but it is far more useful to know how accurate or certain that number is.

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## #10 2012-10-24 09:32:41

Mpmath
Member
Registered: 2012-10-11
Posts: 216

### Re: Infinity multiplied by infinity

Hi;
The most Plausible hypothesis is 0, But if n : infinity = 0 means that n : 0 = infinity, which is impossible.  I think that 0 is the batter hypothesis, But I would not exclude infinity. Answers are many.

Winter is coming.

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## #11 2012-10-24 09:37:15

Mpmath
Member
Registered: 2012-10-11
Posts: 216

### Re: Infinity multiplied by infinity

Regarding the second post  n^3: n = n^2 is a simple formula, applied to infinity shows that infinity*infinity = indeterminate.

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## #12 2012-10-24 09:39:35

bobbym
From: Bumpkinland
Registered: 2009-04-12
Posts: 104,714

### Re: Infinity multiplied by infinity

Hi;

n^3: n = n^2 is a simple formula

You are saying n^3 to n is n^2? What does "to" mean here? I am not following that.

In mathematics, you don't understand things. You just get used to them.
If it ain't broke, fix it until it is.
A number by itself is useful, but it is far more useful to know how accurate or certain that number is.

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## #13 2012-10-24 09:39:58

bob bundy
Moderator
Registered: 2010-06-20
Posts: 7,613

### Re: Infinity multiplied by infinity

hi Mpmath

Can I suggest you type 'divided by' to remove the confusion?

Bob

Children are not defined by school ...........The Fonz
You cannot teach a man anything;  you can only help him find it within himself..........Galileo Galilei

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## #14 2012-10-24 09:41:19

Mpmath
Member
Registered: 2012-10-11
Posts: 216

### Re: Infinity multiplied by infinity

Sorry, this means n^3 divided n= n^2.

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## #15 2012-10-24 09:42:21

Mpmath
Member
Registered: 2012-10-11
Posts: 216

### Re: Infinity multiplied by infinity

By the way, I Will use dividev by from now, thanks!

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## #16 2012-10-24 09:52:14

bobbym
From: Bumpkinland
Registered: 2009-04-12
Posts: 104,714

### Re: Infinity multiplied by infinity

Yes, that is what I thought. Okay, you can divide n^3 by n as long as n does not equal 0 or ∞.

is indeterminate.

In mathematics, you don't understand things. You just get used to them.
If it ain't broke, fix it until it is.
A number by itself is useful, but it is far more useful to know how accurate or certain that number is.

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## #17 2012-10-24 17:00:05

Mpmath
Member
Registered: 2012-10-11
Posts: 216

### Re: Infinity multiplied by infinity

Yes, that's what I was thinking.

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## #18 2012-10-24 17:51:56

bobbym
From: Bumpkinland
Registered: 2009-04-12
Posts: 104,714

### Re: Infinity multiplied by infinity

But

In mathematics, you don't understand things. You just get used to them.
If it ain't broke, fix it until it is.
A number by itself is useful, but it is far more useful to know how accurate or certain that number is.

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## #19 2012-10-24 17:54:50

Mpmath
Member
Registered: 2012-10-11
Posts: 216

### Re: Infinity multiplied by infinity

Ok. This is most Plausible hypothesis.

Winter is coming.

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## #20 2012-10-24 17:58:11

bobbym
From: Bumpkinland
Registered: 2009-04-12
Posts: 104,714

### Re: Infinity multiplied by infinity

Hi;

Yes, infinity is not a number. Some programming languages say NAN for it. Therefore, you can not add or subtract or perform any other type of arithmetic on it and expects consistent results with the number system. There is a small movement in mathematics, but growing, to eliminate it entirely.

In mathematics, you don't understand things. You just get used to them.
If it ain't broke, fix it until it is.
A number by itself is useful, but it is far more useful to know how accurate or certain that number is.

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## #21 2012-10-24 18:23:03

Mpmath
Member
Registered: 2012-10-11
Posts: 216

### Re: Infinity multiplied by infinity

Hi;

This small movement wants to eliminate infinity or operations with infinity?

Winter is coming.

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## #22 2012-10-24 18:32:36

bobbym
From: Bumpkinland
Registered: 2009-04-12
Posts: 104,714

### Re: Infinity multiplied by infinity

Eliminate infinity entirely.

In mathematics, you don't understand things. You just get used to them.
If it ain't broke, fix it until it is.
A number by itself is useful, but it is far more useful to know how accurate or certain that number is.

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## #23 2012-10-24 18:59:55

Mpmath
Member
Registered: 2012-10-11
Posts: 216

### Re: Infinity multiplied by infinity

I think that eliminate infinity is absurd. Infinity is a way to define where numbers and universe can arrive.

Winter is coming.

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## #24 2012-10-24 19:08:01

bobbym
From: Bumpkinland
Registered: 2009-04-12
Posts: 104,714

### Re: Infinity multiplied by infinity

They believe like others that the concept of infinity is full of holes. It really does not belong in mathematics and could be replaced. I am not expert on this part of math and therefore do not know enough to decide who is right.

In mathematics, you don't understand things. You just get used to them.
If it ain't broke, fix it until it is.
A number by itself is useful, but it is far more useful to know how accurate or certain that number is.

Offline

## #25 2012-10-24 20:10:30

Mpmath
Member
Registered: 2012-10-11
Posts: 216

### Re: Infinity multiplied by infinity

Well, no one can decide what is better Regarding infinity, we can only have a theory.

Winter is coming.

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