# Parital fractions?

1. Nov 7, 2006

### pivoxa15

I have never remebered the different partial fraction forumlas. Is there a way to decide which partial fraction formula to use just by looking at the expression?

2. Nov 7, 2006

### Office_Shredder

Staff Emeritus
Partial fraction formulae?

I thought you just did partial fractions... what's the context? Normally you just split the fraction after factoring the denominator into a sum of fractions with denominators equal to the different factored parts

3. Nov 7, 2006

### mathwonk

over R, the only prime polynomials are linear or quadratic. the numerators are either constant or linear respectively.

if f^n is a factor of the denominator, where f is prime, we need to allow for all fractions whose greatest common denom is f^r, so we have

to allow a/f , b/f^2, c/f^3, ...., d/f^n, for appropriate numerators.

e.g. to decom,pose h/[x^2(x^2+x+1)^3] we set it equal to

a/x + b/x^2 + (cx+d)/(x^2+x+1) +(ex+f)/(x^2+x+1)^2 + (gx+h)/(x^2+x+1)^3.

where a,b,c,d,e,f,g,h, are constants.

Last edited: Nov 7, 2006
4. Nov 8, 2006

### pivoxa15

Is that all there is to partial fractions? It isn't as mystifying as it appears.

5. Nov 8, 2006

### arildno

Yes it is!
No, it isn't!