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#1 2010-04-13 04:34:24

Onyx
Member
Registered: 2009-02-24
Posts: 48

partial fraction

Hi, how can I reduce something like the following into partial fractions?

Thanks

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#2 2010-04-13 06:44:27

ZHero
Real Member
Registered: 2008-06-08
Posts: 1,889

Re: partial fraction


If two or more thoughts intersect, there has to be a point!

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#3 2010-04-13 07:43:38

Onyx
Member
Registered: 2009-02-24
Posts: 48

Re: partial fraction

Where does the A and Cx come from? I thought it was simply:

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#4 2010-04-13 07:54:43

rzaidan
Member
Registered: 2009-08-13
Posts: 59

Re: partial fraction

Dear ZHero
I think that it is not easy (or say impossible) to write this fraction into partial fractions as you did,since the fraction which contains in its numerator Cx is not allowed because the denominator contains a linear factor repeated twice , and the appropriate fraction must contain a constant in its numerator, and the purpose of this stratigy is to find the integral of this fraction, and it is easy to find the integral of this fraction by means of substitution u = (aX+b) and continue
Best Wishes
Riad Zaidan

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#5 2010-04-13 07:56:26

rzaidan
Member
Registered: 2009-08-13
Posts: 59

Re: partial fraction

Dear Onyx
As you wrote you will have as  A =0  and  B=1
salam
Riad Zaidan

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#6 2010-04-13 17:49:18

ZHero
Real Member
Registered: 2008-06-08
Posts: 1,889

Re: partial fraction

rzaidan wrote:

. . . the fraction which contains in its numerator Cx is not allowed because the denominator contains a linear factor repeated twice . . .

well.. i think its perfectly allowed as long as the Degree of Numerator is less than that of the Denominator!
however.. i just forgot to include another D in the expression above!

i'll correct it...


note: A=0

Last edited by ZHero (2010-04-13 17:52:19)


If two or more thoughts intersect, there has to be a point!

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#7 2010-04-13 18:32:21

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

Re: partial fraction

Hi

Solving we get an answer with 1 free parameter B.

Substituting into ZHero's RHS.

This is clearly true for all B, so this is an identity. It is also not of much use as a partial fraction.


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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#8 2010-04-13 19:20:43

ZHero
Real Member
Registered: 2008-06-08
Posts: 1,889

Re: partial fraction

bobbym wrote:

It is also not of much use as a partial fraction.

this is probably coz Numerator is 1!


If two or more thoughts intersect, there has to be a point!

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#9 2010-04-15 07:01:35

Onyx
Member
Registered: 2009-02-24
Posts: 48

Re: partial fraction

Thanks, it seems this partial fraction doesn't make anything simpler at all, but I found another way to solve my problem. I do however have another partial fraction:

I thought something like this was written as:

I haven't seen partial fractions written with a constant as a term in its own right (As the term 'A' is in your example) before, and also thought the form Bx+C in a numerator was only used for squared variables within the parenthesis such as:

Is the form I have provided not correct?

Last edited by Onyx (2010-04-15 07:02:09)

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#10 2010-04-15 07:06:29

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

Re: partial fraction

Hi Onyx;

That form will work.


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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