How do you express ( 2x)/(1-x^3) in partial fractions?

1 Answer
Mar 14, 2016

2/(3(1-x)) +(2(x-1))/(3(1+x+x^2)

Explanation:

Write (2x)/(1-x^3) = A/(1-x) + (Bx+C)/(1+x+x^2)

On simplifying the Right Hand Side and comparing the coefficients
on both sides it would be

2x= A+Ax +Ax^2 +Bx-Bx^2+C-Cx, so that,
A-B=0, A+C=0 and A+B-C=2

Add the first two equation to get B-C= 2A.
Plug in this value in the next equation to get 3A=2, that is A=2/3 and hence B= 2/3
and C= -2/3.

The required partial fractions would be
2/(3(1-x)) +(2(x-1))/(3(1+x+x^2)