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## #1 2014-05-09 22:36:07

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

### help me! Q=D={x|x is an integer such that x^2=2)

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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## #2 2014-05-09 22:48:20

zetafunc.
Guest

### Re: help me! Q=D={x|x is an integer such that x^2=2)

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?

## #3 2014-05-09 22:51:59

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

### Re: help me! Q=D={x|x is an integer such that x^2=2)

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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## #4 2014-05-09 22:53:54

Agnishom
Real Member
From: Riemann Sphere
Registered: 2011-01-29
Posts: 24,861
Website

### Re: help me! Q=D={x|x is an integer such that x^2=2)

The set is

Welcome to the forum;

'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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## #5 2014-05-09 23:02:54

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

### Re: help me! Q=D={x|x is an integer such that x^2=2)

Agnishom wrote:

The set is

Welcome to the forum;

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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## #6 2014-05-10 00:27:47

bob bundy
Registered: 2010-06-20
Posts: 8,632

### Re: help me! Q=D={x|x is an integer such that x^2=2)

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
Sometimes I deliberately make mistakes, just to test you!  …………….Bob Bundy

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## #7 2014-05-10 00:37:16

Agnishom
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From: Riemann Sphere
Registered: 2011-01-29
Posts: 24,861
Website

### Re: help me! Q=D={x|x is an integer such that x^2=2)

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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## #8 2014-05-10 01:07:01

bob bundy
Registered: 2010-06-20
Posts: 8,632

### Re: help me! Q=D={x|x is an integer such that x^2=2)

All questions are worthy questions.

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
Sometimes I deliberately make mistakes, just to test you!  …………….Bob Bundy

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## #9 2014-05-10 01:18:56

Agnishom
Real Member
From: Riemann Sphere
Registered: 2011-01-29
Posts: 24,861
Website

### Re: help me! Q=D={x|x is an integer such that x^2=2)

Axiom: All questions are worthy.

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

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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## #10 2014-05-10 05:40:00

bob bundy
Registered: 2010-06-20
Posts: 8,632

### Re: help me! Q=D={x|x is an integer such that x^2=2)

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
Sometimes I deliberately make mistakes, just to test you!  …………….Bob Bundy

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## #11 2014-05-10 05:44:37

Agnishom
Real Member
From: Riemann Sphere
Registered: 2011-01-29
Posts: 24,861
Website

### Re: help me! Q=D={x|x is an integer such that x^2=2)

yay!

'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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## #12 2014-05-10 06:11:02

bob bundy
Registered: 2010-06-20
Posts: 8,632

### Re: help me! Q=D={x|x is an integer such that x^2=2)

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

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
Sometimes I deliberately make mistakes, just to test you!  …………….Bob Bundy

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## #13 2014-05-10 12:25:45

Agnishom
Real Member
From: Riemann Sphere
Registered: 2011-01-29
Posts: 24,861
Website

### Re: help me! Q=D={x|x is an integer such that x^2=2)

Not necessarily.

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

'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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## #14 2014-05-10 13:37:16

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

### Re: help me! Q=D={x|x is an integer such that x^2=2)

bob bundy wrote:

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

Bob

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## #15 2014-05-10 20:13:51

bob bundy
Registered: 2010-06-20
Posts: 8,632

### Re: help me! Q=D={x|x is an integer such that x^2=2)

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

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
Sometimes I deliberately make mistakes, just to test you!  …………….Bob Bundy

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## #16 2014-05-14 13:17:28

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

### Re: help me! Q=D={x|x is an integer such that x^2=2)

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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## #17 2014-05-14 19:14:07

bob bundy
Registered: 2010-06-20
Posts: 8,632

### Re: help me! Q=D={x|x is an integer such that x^2=2)

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

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
Sometimes I deliberately make mistakes, just to test you!  …………….Bob Bundy

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## #18 2014-05-14 19:28:26

Agnishom
Real Member
From: Riemann Sphere
Registered: 2011-01-29
Posts: 24,861
Website

### Re: help me! Q=D={x|x is an integer such that x^2=2)

Can we name it 'Fundamental Theorem of Worth'?

'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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## #19 2014-05-15 10:15:47

bob bundy
Registered: 2010-06-20
Posts: 8,632

### Re: help me! Q=D={x|x is an integer such that x^2=2)

Fundamental Theorem of Worth it is then.  Congratulations.

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
Sometimes I deliberately make mistakes, just to test you!  …………….Bob Bundy

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## #20 2014-05-15 13:01:47

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

### Re: help me! Q=D={x|x is an integer such that x^2=2)

Prove the theorem. I thought it was an axiom.

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## #21 2014-05-20 00:29:13

bob bundy
Registered: 2010-06-20
Posts: 8,632

### Re: help me! Q=D={x|x is an integer such that x^2=2)

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

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
Sometimes I deliberately make mistakes, just to test you!  …………….Bob Bundy

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## #22 2014-05-20 00:33:58

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

### Re: help me! Q=D={x|x is an integer such that x^2=2)

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

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## #23 2014-05-20 01:05:19

bob bundy
Registered: 2010-06-20
Posts: 8,632

### Re: help me! Q=D={x|x is an integer such that x^2=2)

We have an axiom:

Agnishom wrote:

Axiom: All questions are 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
Sometimes I deliberately make mistakes, just to test you!  …………….Bob Bundy

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## #24 2014-05-20 01:06:08

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

### Re: help me! Q=D={x|x is an integer such that x^2=2)

A theory is usually supported by some empirical evidence.

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## #25 2014-05-20 02:00:45

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

### Re: help me! Q=D={x|x is an integer such that x^2=2)

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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