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## #1 2008-10-23 17:48:55

MathsIsFun
Registered: 2005-01-21
Posts: 7,685

### Factoring - Introduction

A new page: Factoring - Introduction

It does not cover the subject very well, I know! But is it a good start?

"The physicists defer only to mathematicians, and the mathematicians defer only to God ..."  - Leon M. Lederman

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## #2 2008-10-23 18:40:12

ganesh
Registered: 2005-06-28
Posts: 26,149

### Re: Factoring - Introduction

A real elegant way of starting! But there's more to be covered, like factoring quadratic equations, and higher degree equations.

It is no good to try to stop knowledge from going forward. Ignorance is never better than knowledge - Enrico Fermi.

Nothing is better than reading and gaining more and more knowledge - Stephen William Hawking.

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## #3 2008-10-24 08:00:52

JaneFairfax
Member
Registered: 2007-02-23
Posts: 6,868

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## #4 2008-10-24 10:27:30

mathsyperson
Moderator
Registered: 2005-06-22
Posts: 4,900

### Re: Factoring - Introduction

In the UK we also use -ise, not -ize.

Nice page though! Well explained, as always.
Once you get advanced enough, I think this method for turning general quadratic questions into monic ones would be useful:

Say you have 2x² + 7x + 3.
Find two numbers that add to give 7, and multiply to give 2*3 = 6.
(ie. factorise y² + 7y + 6)

Rewrite 7x using these:
2x² + 6x + x + 3.

Factorise the first two and last two terms separately:
2x(x+3) + (x+3).

If you've done this correctly, your two new terms should have a clearly visible common factor. Factorise again and you're finished:

(2x+1)(x+3)

Why did the vector cross the road?
It wanted to be normal.

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## #5 2008-10-24 10:34:30

careless25
Real Member
Registered: 2008-07-24
Posts: 559

### Re: Factoring - Introduction

mathsyperson
that method is called factor by grouping in US.

Nice page Mathisfun!
Other method is completing the square.

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## #6 2008-10-24 10:41:41

JaneFairfax
Member
Registered: 2007-02-23
Posts: 6,868

### Re: Factoring - Introduction

mathsyperson wrote:

In the UK we also use -ise, not -ize.

Yes, we DO use -ize! We use both interchangeably.

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## #7 2008-10-24 10:55:23

careless25
Real Member
Registered: 2008-07-24
Posts: 559

### Re: Factoring - Introduction

MathIsFun i think you should change the title to "How to Factor' to avoid controversy.

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## #8 2008-10-24 12:37:59

MathsIsFun
Registered: 2005-01-21
Posts: 7,685

### Re: Factoring - Introduction

Mathsy: thanks, I will put that in.

careless25: Not a bad idea. Or maybe another "language note".

"The physicists defer only to mathematicians, and the mathematicians defer only to God ..."  - Leon M. Lederman

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## #9 2008-10-24 14:07:23

JaneFairfax
Member
Registered: 2007-02-23
Posts: 6,868

### Re: Factoring - Introduction

careless25 wrote:

MathIsFun i think you should change the title to "How to Factor' to avoid controversy.

Why do you still not get it? I said: In Britain, we DO NOT SAY How to factor, we say How to factorize/-ise!!

Last edited by JaneFairfax (2008-10-24 15:04:03)

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## #10 2008-10-24 14:44:23

careless25
Real Member
Registered: 2008-07-24
Posts: 559

### Re: Factoring - Introduction

Sry Jane!
I was just trying to avoid controversy.:|
Any ideas for the title then?

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## #11 2008-10-24 17:02:40

MathsIsFun
Registered: 2005-01-21
Posts: 7,685

### Re: Factoring - Introduction

Careless: good try ... you suggested "Factor" as a way between Factorizing and Factoring, but it didn't quite work.

Jane: you are quite right of course, and somewhat more restrained, which is good. Let people make suggestions, and save CAPS for the really nasty people

I think my "language note" should work.

Mathsy: I think I will make a new page on "Factoring Quadratics". I will most likely need many pages to cover this topic.

"The physicists defer only to mathematicians, and the mathematicians defer only to God ..."  - Leon M. Lederman

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## #12 2008-10-24 21:58:44

Devantè
Real Member
Registered: 2006-07-14
Posts: 6,400

### Re: Factoring - Introduction

Meh, language... it is a concept that would be much simpler if anyone applied themselves to the same rule

Nice page. ^_^

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## #13 2008-10-28 15:13:19

MathsIsFun
Registered: 2005-01-21
Posts: 7,685

### Re: Factoring - Introduction

I have updated: Factoring - Introduction

Is that page OK? Did I make any mistakes?

"The physicists defer only to mathematicians, and the mathematicians defer only to God ..."  - Leon M. Lederman

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## #14 2008-10-29 01:03:57

mathsyperson
Moderator
Registered: 2005-06-22
Posts: 4,900

### Re: Factoring - Introduction

I'm still not sure about 'factorize'.
Jane didn't like factor because that's an Americanism, but -ize is an Americanism too.

Nice page though! Perhaps a bit more texty than some of the other pages, but that's unavoidable with higher level topics. I think a mention of completing the square would be good, since the quadratic formula came from completing the square on a general equation.

(Also, you didn't need to credit me. It's not like I invented that method or anything.)

Why did the vector cross the road?
It wanted to be normal.

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## #15 2008-10-29 23:08:28

careless25
Real Member
Registered: 2008-07-24
Posts: 559

### Re: Factoring - Introduction

NIce pages MathISFun but i think you should put why we factor and graphs so its easier to understand.
So for instance when we factor or factorize quadratic its easier for us to find the intercepts.
or you could just make a page abput solvind linera/quadratic equation.

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## #16 2008-10-30 10:22:41

MathsIsFun
Registered: 2005-01-21
Posts: 7,685

### Re: Factoring - Introduction

Thanks both of you! Good suggestions.

"The physicists defer only to mathematicians, and the mathematicians defer only to God ..."  - Leon M. Lederman

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## #17 2008-12-25 10:02:54

wasabi
Member
Registered: 2008-08-14
Posts: 5

### Re: Factoring - Introduction

JaneFairfax wrote:
careless25 wrote:

MathIsFun i think you should change the title to "How to Factor' to avoid controversy.

Why do you still not get it? I said: In Britain, we DO NOT SAY How to factor, we say How to factorize/-ise!!

Geeez language....make me crazy !!!

Get out of your comfort zone to see the brighter horizon

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## #18 2008-12-25 16:19:09

ganesh
Registered: 2005-06-28
Posts: 26,149

### Re: Factoring - Introduction

MathsIsFun,
Could we go one step further and try to explain the possible methods of factorizing cubic/quartic equations etc. in a simple way?

It is no good to try to stop knowledge from going forward. Ignorance is never better than knowledge - Enrico Fermi.

Nothing is better than reading and gaining more and more knowledge - Stephen William Hawking.

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## #19 2008-12-25 22:45:13

MathsIsFun
Registered: 2005-01-21
Posts: 7,685

### Re: Factoring - Introduction

Most certainly, but it will be some time before I could get around to it ... would you like to have a go?

"The physicists defer only to mathematicians, and the mathematicians defer only to God ..."  - Leon M. Lederman

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## #20 2008-12-26 01:53:31

ganesh
Registered: 2005-06-28
Posts: 26,149

### Re: Factoring - Introduction

Sure.....
I guess I can start the work this Sunday evening, and e-mail you in parts....
Feel free to edit it, and tell me what needs to be added....what is to be omitted can be done by you without bothering to inform me;
But please give the finishing touch!

It is no good to try to stop knowledge from going forward. Ignorance is never better than knowledge - Enrico Fermi.

Nothing is better than reading and gaining more and more knowledge - Stephen William Hawking.

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## #21 2008-12-26 08:14:47

MathsIsFun
Registered: 2005-01-21
Posts: 7,685

### Re: Factoring - Introduction

Sounds great!

"The physicists defer only to mathematicians, and the mathematicians defer only to God ..."  - Leon M. Lederman

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