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## #1 2013-05-19 18:43:24

{7/3}
Member
Registered: 2013-02-11
Posts: 210

### Continuous functions

I have been give a function f(x)=3x^3+x-2,how do i show it is a continuous function?

There are 10 kinds of people in the world,people who understand binary and people who don't.

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## #2 2013-05-19 22:03:23

bobbym
bumpkin
From: Bumpkinland
Registered: 2009-04-12
Posts: 109,606

### Re: Continuous functions

Hi;

All polynomials are continuous.

You might try here and see if you like his proof:

http://www.proofwiki.org/wiki/Polynomial_is_Continuous

In mathematics, you don't understand things. You just get used to them.
If it ain't broke, fix it until it is.
Always satisfy the Prime Directive of getting the right answer above all else.

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## #3 2013-05-19 22:28:07

{7/3}
Member
Registered: 2013-02-11
Posts: 210

### Re: Continuous functions

I'd love to go to that link but for some reason the link's words look weired and i can't read them.

There are 10 kinds of people in the world,people who understand binary and people who don't.

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## #4 2013-05-19 22:42:05

bobbym
bumpkin
From: Bumpkinland
Registered: 2009-04-12
Posts: 109,606

### Re: Continuous functions

Hi;

Okay, I have a snapshot of it:

Let's see if these will suffice because they are simpler than epsilon delta type proofs.

I am assuming you are talking about continuity in R.

In mathematics, you don't understand things. You just get used to them.
If it ain't broke, fix it until it is.
Always satisfy the Prime Directive of getting the right answer above all else.

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## #5 2013-05-19 23:43:08

{7/3}
Member
Registered: 2013-02-11
Posts: 210

### Re: Continuous functions

Thanks a lot bobbym

There are 10 kinds of people in the world,people who understand binary and people who don't.

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## #6 2013-05-19 23:47:48

bobbym
bumpkin
From: Bumpkinland
Registered: 2009-04-12
Posts: 109,606

### Re: Continuous functions

Hi;

It is really going to depend on how far back they want you to go. If they will accept that any linear function ( ax + b ) is continuous then we are done with the above. If not, you may have to prove the theorem on linear functions first.

Also, somebody else might have a better idea.

In mathematics, you don't understand things. You just get used to them.
If it ain't broke, fix it until it is.
Always satisfy the Prime Directive of getting the right answer above all else.

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## #7 2013-05-20 00:23:29

{7/3}
Member
Registered: 2013-02-11
Posts: 210

### Re: Continuous functions

I know how to prove linear functions are continuous

There are 10 kinds of people in the world,people who understand binary and people who don't.

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## #8 2013-05-20 00:27:46

bobbym
bumpkin
From: Bumpkinland
Registered: 2009-04-12
Posts: 109,606

### Re: Continuous functions

Hi;

Then I think we are done here...

In mathematics, you don't understand things. You just get used to them.
If it ain't broke, fix it until it is.
Always satisfy the Prime Directive of getting the right answer above all else.

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## #9 2013-05-20 01:14:59

bob bundy
Registered: 2010-06-20
Posts: 8,075

### Re: Continuous functions

hi {7/3}

in post 3 you  wrote:

I'd love to go to that link but for some reason the link's words look weired and i can't read them.

The maths appears to be in a Latex like code.  Maybe your browser isn't set to view it properly.  Try View Source.

And I found it took a while for all the code to be interpreted correctly.

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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## #10 2013-05-20 01:28:02

{7/3}
Member
Registered: 2013-02-11
Posts: 210

### Re: Continuous functions

Thanks for the advice,bob bundy,i will try it.

There are 10 kinds of people in the world,people who understand binary and people who don't.

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