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

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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**bobbym****Administrator**- From: Bumpkinland
- Registered: 2009-04-12
- Posts: 105,673

Hi;

All polynomials are continuous.

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

**In mathematics, you don't understand things. You just get used to them.****If it ain't broke, fix it until it is.****No great discovery was ever made without a bold guess. **

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

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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**bobbym****Administrator**- From: Bumpkinland
- Registered: 2009-04-12
- Posts: 105,673

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.****No great discovery was ever made without a bold guess. **

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

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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**bobbym****Administrator**- From: Bumpkinland
- Registered: 2009-04-12
- Posts: 105,673

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.****No great discovery was ever made without a bold guess. **

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

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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**bobbym****Administrator**- From: Bumpkinland
- Registered: 2009-04-12
- Posts: 105,673

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.****No great discovery was ever made without a bold guess. **

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**bob bundy****Moderator**- Registered: 2010-06-20
- Posts: 7,657

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

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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