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**zee-f****Member**- Registered: 2011-05-12
- Posts: 1,220

i showed what i did

x^2-3x-18=

x^2-6x-3x-18

x(x-6)-3(x-6)

(x-3)(x-6)

One, who adopts patience, will never be deprived of success though it may take a long time to reach him. Imam ali (as)<3

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**bobbym****Administrator**- From: Bumpkinland
- Registered: 2009-04-12
- Posts: 86,786

-6 x - 3 x = -9 x not -3 x

**In mathematics, you don't understand things. You just get used to them.Of course that result can be rigorously obtained, but who cares?Combinatorics is Algebra and Algebra is Combinatorics.**

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**zee-f****Member**- Registered: 2011-05-12
- Posts: 1,220

dont i have to factor x^2-6x

i used the method anonimnystefy used

One, who adopts patience, will never be deprived of success though it may take a long time to reach him. Imam ali (as)<3

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**bobbym****Administrator**- From: Bumpkinland
- Registered: 2009-04-12
- Posts: 86,786

Yes, but you have to group so that it so that it still equals the original polynomial.

x^2-6x-3x-18 does not equal x^2-3x-18

**In mathematics, you don't understand things. You just get used to them.Of course that result can be rigorously obtained, but who cares?Combinatorics is Algebra and Algebra is Combinatorics.**

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**bobbym****Administrator**- From: Bumpkinland
- Registered: 2009-04-12
- Posts: 86,786

Hi zeef

Try this grouping:

x^2 + 3x - 6x - 18

**In mathematics, you don't understand things. You just get used to them.Of course that result can be rigorously obtained, but who cares?Combinatorics is Algebra and Algebra is Combinatorics.**

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**zee-f****Member**- Registered: 2011-05-12
- Posts: 1,220

thats ganna give me

x(x+3)-3(2x-6)

One, who adopts patience, will never be deprived of success though it may take a long time to reach him. Imam ali (as)<3

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**bobbym****Administrator**- From: Bumpkinland
- Registered: 2009-04-12
- Posts: 86,786

Hi;

Not exactly, do it this way:

x ( x + 3 ) - 6 ( x + 3 )

( x + 3 ) ( x - 6 ) is the factorization.

Of course that result can be rigorously obtained, but who cares?

Combinatorics is Algebra and Algebra is Combinatorics.

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**bob bundy****Moderator**- Registered: 2010-06-20
- Posts: 6,395

hi zee-f

You wrote:

does anybody know a good website that teaches you Factoring Polynomials using grouping

and bobbym wrote:

I can not think of a better one than here.

Of course I agree with this ... and who better to help than bobbym.

But, having said that you might like to look at

http://www.youtube.com/watch?v=2Q8lG1WaqJY

There are three examples there that take you through a prescriptive method using grouping.

Bob

*Last edited by bob bundy (2011-07-21 19:52:46)*

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

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**zee-f****Member**- Registered: 2011-05-12
- Posts: 1,220

ok so this is what the question says Factor problems 9 - 12 by using the difference of squares method. what on earth does that mean ????

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**bobbym****Administrator**- From: Bumpkinland
- Registered: 2009-04-12
- Posts: 86,786

Hi bob bundy;

and who better to help than bobbym

Yikes! Let me tell you about him. Took two bullets straight through his head in 67. Yes clean through, nowadays people use his head in place of binoculars. I mean should we listen to a guy who the wind does not have to go around his head?

Hi zee-f;

Can you please bring those problems down here? Did you watch bob bundy's video?

Of course that result can be rigorously obtained, but who cares?

Combinatorics is Algebra and Algebra is Combinatorics.

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**zee-f****Member**- Registered: 2011-05-12
- Posts: 1,220

yup i willl but i dont just want the answer i want help on the method plz

9. x^2 4

AThis polynomial cannot be factored by using the difference of squares method.

B(x 2)(x 2)

C(x 2)(x 1)

D(x 2)(x + 2)

E(x 1)(x 4)

F(x + 2)(x + 2)

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**bobbym****Administrator**- From: Bumpkinland
- Registered: 2009-04-12
- Posts: 86,786

Hi;

I like D) here is why.

http://www.mathsisfun.com/algebra/speci … ducts.html

http://www.mathsisfun.com/algebra/factoring.html

And then go here and you will know as much about it as I do!

Of course that result can be rigorously obtained, but who cares?

Combinatorics is Algebra and Algebra is Combinatorics.

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**zee-f****Member**- Registered: 2011-05-12
- Posts: 1,220

thanx allllot am ganna see the links and do the rest of the problems ill submit my answers tomorrow to make sure thanx allot guyyys

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**bobbym****Administrator**- From: Bumpkinland
- Registered: 2009-04-12
- Posts: 86,786

Okay! I will wait to see your answers. And please watch the video! I am watching it now.

Of course that result can be rigorously obtained, but who cares?

Combinatorics is Algebra and Algebra is Combinatorics.

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**bob bundy****Moderator**- Registered: 2010-06-20
- Posts: 6,395

hi zee-f

Difference of two squares.

When there is no 'x' term, it has disappeared because there was a plus term and a minus term that cancelled out. (see picture)

That leaves an x squared term and a minus term, which will also be a perfect square. (in my diagram '4' is a perfect square because it is 4 = 2 x 2 )

So you have the difference of two squares, x squared and two squared.

Does that help you to see which answer MUST be correct?

Bob

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

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**zee-f****Member**- Registered: 2011-05-12
- Posts: 1,220

hey guys thanx allot for all this help and sources it helped me solve my problems this is what i got

for #9 i got d and 10-D 11-E 12-D

Factor problems 9 - 12 by using the difference of squares method.

9. x^2 4

AThis polynomial cannot be factored by using the difference of squares method.

B(x 2)(x 2)

C(x 2)(x 1)

D(x 2)(x + 2)

E(x 1)(x 4)

F(x + 2)(x + 2)

10. x^2 25

A(-x 5)(x - 5)

BThis polynomial cannot be factored by using the difference of squares method.

C(-x + 5)(x + 5)

D(x 5)(x + 5)

E(x + 5)(-x - 5)

F(x 5)(x - 5)

11. 36x^4 4x^2

A(6x^2 2x)(6x^2 - 2x)

B(6x^2 + 2x)(6x^2 + 2x)

CThis polynomial cannot be factored by using the difference of squares method.

D(-6x^2 2x)(-6x^2 - 2x)

E(6x^2 2x)(6x^2 + 2x)

F(-6x^2 + 2x)(6x^2 - 2x)

12. x^2 + 100

A(x + 10)(x 10)

B(-x + 10)(x 10)

C(x + 10)(x + 10)

DThis polynomial cannot be factored by using the difference of squares method.

E(x - 10)(x 10)

F(-x + 10)(-x 10)

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**anonimnystefy****Real Member**- From: The Foundation
- Registered: 2011-05-23
- Posts: 15,532

all is correct.good job.

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

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**zee-f****Member**- Registered: 2011-05-12
- Posts: 1,220

thanx to u guys i got them correct thanx allot

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**zee-f****Member**- Registered: 2011-05-12
- Posts: 1,220

i was wondering is the perfect squares method different from this method ?

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**bobbym****Administrator**- From: Bumpkinland
- Registered: 2009-04-12
- Posts: 86,786

Hi zee-f;

You did well!

Of course that result can be rigorously obtained, but who cares?

Combinatorics is Algebra and Algebra is Combinatorics.

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**zee-f****Member**- Registered: 2011-05-12
- Posts: 1,220

thanx bobbym

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**bobbym****Administrator**- From: Bumpkinland
- Registered: 2009-04-12
- Posts: 86,786

Did you get around to watching that video?

Of course that result can be rigorously obtained, but who cares?

Combinatorics is Algebra and Algebra is Combinatorics.

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**zee-f****Member**- Registered: 2011-05-12
- Posts: 1,220

the grouping video yup it was really good he made the method reallly easy

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**bobbym****Administrator**- From: Bumpkinland
- Registered: 2009-04-12
- Posts: 86,786

Yes, I watched it too and liked it.

Of course that result can be rigorously obtained, but who cares?

Combinatorics is Algebra and Algebra is Combinatorics.

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**zee-f****Member**- Registered: 2011-05-12
- Posts: 1,220

do u have any good links on the perfect squares method isn't like different from the difference of squares method.

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