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#1 2014-05-20 04:17:41

juxta
Member
Registered: 2012-05-19
Posts: 2

Functions

Hello everyone, its has been a while since i last visited. I have a small problem on functions at the moment, I looked over the internet but couldn't find the solution to this small problem. So here is the problem, in the picture below:

functionmapping.png

Is this a valid function? Where 'b' can go twice to the range? I looked at the answers from my question sheet and it said it is not a surjection :S

Kind Regards smile

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#2 2014-05-20 04:20:40

bobbym
Administrator
From: Bumpkinland
Registered: 2009-04-12
Posts: 96,613

Re: Functions


In mathematics, you don't understand things. You just get used to them.

If it ain't broke, fix it until it is.

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#3 2014-05-20 04:24:11

Agnishom
Real Member
From: Riemann Sphere
Registered: 2011-01-29
Posts: 21,748
Website

Re: Functions

It is not a function.

A function is a relation that relates every element of the domain to exactly one element of the co-domain.


'And fun? If maths is fun, then getting a tooth extraction is fun. A viral infection is fun. Rabies shots are fun.'
'God exists because Mathematics is consistent, and the devil exists because we cannot prove it'
'But our love is like the wind. I can't see it but I can feel it.' -A Walk to remember

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#4 2014-05-20 05:02:42

juxta
Member
Registered: 2012-05-19
Posts: 2

Re: Functions

THANK YOU SO MUCH! Thanks for the link as well, didn't know about this.

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#5 2014-05-20 05:28:46

bobbym
Administrator
From: Bumpkinland
Registered: 2009-04-12
Posts: 96,613

Re: Functions

You are welcome.


In mathematics, you don't understand things. You just get used to them.

If it ain't broke, fix it until it is.

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#6 2014-05-20 07:59:54

ShivamS
Member
Registered: 2011-02-07
Posts: 3,646

Re: Functions

What does it being surjective have anything to do with it being a function? Anyway, to tell if it is a surjective function, we need it's codomain.

Agnishom wrote:

It is not a function.

A function is a relation that relates every element of the domain to exactly one element of the co-domain.

No, you mean range or image.

Last edited by ShivamS (2014-05-20 08:02:38)

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#7 2014-05-20 12:46:20

Agnishom
Real Member
From: Riemann Sphere
Registered: 2011-01-29
Posts: 21,748
Website

Re: Functions

Range is that subset of the codomain which consists of all those and only all those elements on which something has been mapped.

https://brilliant.org/discussions/threa … rminology/


'And fun? If maths is fun, then getting a tooth extraction is fun. A viral infection is fun. Rabies shots are fun.'
'God exists because Mathematics is consistent, and the devil exists because we cannot prove it'
'But our love is like the wind. I can't see it but I can feel it.' -A Walk to remember

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#8 2014-05-20 12:56:30

ShivamS
Member
Registered: 2011-02-07
Posts: 3,646

Re: Functions

What about it?

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#9 2014-05-20 13:00:54

ShivamS
Member
Registered: 2011-02-07
Posts: 3,646

Re: Functions

As an added note, you are assuming that all functions are surjective. That is not the case.

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#10 2014-05-20 14:27:38

Agnishom
Real Member
From: Riemann Sphere
Registered: 2011-01-29
Posts: 21,748
Website

Re: Functions


'And fun? If maths is fun, then getting a tooth extraction is fun. A viral infection is fun. Rabies shots are fun.'
'God exists because Mathematics is consistent, and the devil exists because we cannot prove it'
'But our love is like the wind. I can't see it but I can feel it.' -A Walk to remember

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#11 2014-05-20 23:32:59

ShivamS
Member
Registered: 2011-02-07
Posts: 3,646

Re: Functions

So?

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