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**caspertts****Member**- Registered: 2014-05-09
- Posts: 3

first of all, hello I'm new here and I'm not good in math so I decided to join this forum,hope we can help each other!

this is the question that I don't know the answer

D={x|x is an integer such that x^2=2)

list the elements of D

if I √2, I will not get the value of x in integer isn't?

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**zetafunc.****Guest**

caspertts wrote:

if I √2, I will not get the value of x in integer isn't?

So what can you say about the set, D?

**caspertts****Member**- Registered: 2014-05-09
- Posts: 3

zetafunc. wrote:

caspertts wrote:if I √2, I will not get the value of x in integer isn't?

So what can you say about the set, D?

containt no element?

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The set is

Welcome to the forum;

What is your favorite color?

'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'

I'm not crazy, my mother had me tested.

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**caspertts****Member**- Registered: 2014-05-09
- Posts: 3

Agnishom wrote:

The set is

Welcome to the forum;

What is your favorite color?

thanks!my next question,if

A={1}

D={∅}

then A∩D?

sorry for asking simple question like this , favorite color?blue!

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**bob bundy****Administrator**- Registered: 2010-06-20
- Posts: 8,407

hi caspertts

Welcome to the forum.

A intersection 'phi' is everything in both. But they haven't got any common elements so it's the empty set again.

Have a look here:

http://www.mathsisfun.com/sets/sets-introduction.html

If that's too simple then use the search with the word 'sets' to find lots more.

Bob

Strictly speaking the empty set is { } not {phi}. There is a difference which I'll explain if you want.

*Last edited by bob bundy (2014-05-10 00:30:59)*

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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sorry for asking simple question like this

Do not be sorry. All questions are worthy questions.

Yoda wrote:

A fool, no questioner is. By asking, wiser he becomes.

'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'

I'm not crazy, my mother had me tested.

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**bob bundy****Administrator**- Registered: 2010-06-20
- Posts: 8,407

All questions are worthy questions.

I agree with your sentiment but what about:

Is it FALSE to say this question is worthy?

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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Axiom: All questions are worthy.

Question: Is it FALSE to say this question is worthy?

Answer: No. [by axiom]

Which part of the axiom is contradicted?

'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'

I'm not crazy, my mother had me tested.

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**bob bundy****Administrator**- Registered: 2010-06-20
- Posts: 8,407

I concede your point.

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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yay!

'God exists because Mathematics is consistent, and the devil exists because we cannot prove it'

I'm not crazy, my mother had me tested.

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**bob bundy****Administrator**- Registered: 2010-06-20
- Posts: 8,407

Don't get too happy. I may yet find a sentence that does what I was intending.

Bob

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

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Not necessarily.

There are undoubtedly properties about questions which you cannot prove false.Example: All questions end with a question mark

'God exists because Mathematics is consistent, and the devil exists because we cannot prove it'

I'm not crazy, my mother had me tested.

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**ShivamS****Member**- Registered: 2011-02-07
- Posts: 3,648

bob bundy wrote:

Don't get too happy. I

mayyet find a sentence that does what I was intending.Bob

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**bob bundy****Administrator**- Registered: 2010-06-20
- Posts: 8,407

hi Agnishom,

After much further thought, I find I am able to find any inconsistency or logical flaw in your theory. I therefore hold it to be a good theory.

Do you want to name it? How about "Agnishom's First Worthiness Theory"?

Bob

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

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**ShivamS****Member**- Registered: 2011-02-07
- Posts: 3,648

bob bundy wrote:

I find I am able to find any inconsistency or logical flaw in your theory.

Your post does not make sense

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**bob bundy****Administrator**- Registered: 2010-06-20
- Posts: 8,407

O yes. Meant to be 'unable to find'. Whoops.

Bob

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

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Can we name it 'Fundamental Theorem of Worth'?

'God exists because Mathematics is consistent, and the devil exists because we cannot prove it'

I'm not crazy, my mother had me tested.

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**bob bundy****Administrator**- Registered: 2010-06-20
- Posts: 8,407

**Fundamental Theorem of Worth** it is then. Congratulations.

Bob

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

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**ShivamS****Member**- Registered: 2011-02-07
- Posts: 3,648

Prove the theorem. I thought it was an axiom.

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**bob bundy****Administrator**- Registered: 2010-06-20
- Posts: 8,407

ShivamS wrote:

Prove the theorem. I thought it was an axiom.

You are right. Let's amend it to: "**Fundamental Theory of Worth**."

Is that OK ?

Bob

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

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**ShivamS****Member**- Registered: 2011-02-07
- Posts: 3,648

It has not been proven. It must be an axiom or a hypothesis.

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**bob bundy****Administrator**- Registered: 2010-06-20
- Posts: 8,407

We have an axiom:

Agnishom wrote:

Axiom: All questions are worthy.

Bob

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

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**ShivamS****Member**- Registered: 2011-02-07
- Posts: 3,648

A theory is usually supported by some empirical evidence.

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**anonimnystefy****Real Member**- From: Harlan's World
- Registered: 2011-05-23
- Posts: 16,039

Not really. Number theory, for example.

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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