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#1 2008-11-29 01:00:59

GemmaJ1988
Member
Registered: 2008-10-08
Posts: 39

factorise

hey can anyone factorise the following equation:

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#2 2008-11-29 01:04:33

x.gurl.x
Member
Registered: 2008-11-29
Posts: 1

Re: factorise

Um i'm not s sure.....

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#3 2008-11-29 01:10:30

Daniel123
Member
Registered: 2007-05-23
Posts: 663

Re: factorise

First of all, factor -1 out:

-(x^3 + 3x + 4)

Now it should be fairy easy to spot that - 1 is a root and so, by the factor theorem, (x+1) is a factor.

-(x+1)(Ax^2 + Bx + C)

From here, you could use long division to find the values of A, B and C, or you could mutliply out and equate coeffients.

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#4 2008-11-29 02:17:51

GemmaJ1988
Member
Registered: 2008-10-08
Posts: 39

Re: factorise

i've factorised it to get:


is it possible to factorise again?

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#5 2008-11-29 03:06:05

Daniel123
Member
Registered: 2007-05-23
Posts: 663

Re: factorise

You should have a minus on the outside as well.

Assuming what you have done is correct (you can try it by plugging a few values in), then no, that won't factorise nicely.

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#6 2009-04-12 12:07:14

bobbym
bumpkin
From: Bumpkinland
Registered: 2009-04-12
Posts: 109,606

Re: factorise

Hi;

   The factors of (x^2-x+4) are complex so that is the best you can do.

bobbym


In mathematics, you don't understand things. You just get used to them.
If it ain't broke, fix it until it is.
Always satisfy the Prime Directive of getting the right answer above all else.

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