# Math Help - sum of power series problem

1. ## sum of power series problem

Express the function as the sum of a power series by first using partial fractions, find the interval of convergence.

f(x) = 3/(x^2 +x - 2)

thanks for any help with this one.

..partial fraction would be: 3/(x-1) + 3/(x+2)
i think.

2. Originally Posted by rcmango
Express the function as the sum of a power series by first using partial fractions, find the interval of convergence.

f(x) = 3/(x^2 +x - 2)

thanks for any help with this one.

..partial fraction would be: 3/(x-1) + 3/(x+2)
i think.

your partial fractions are wrong. find the correct ones, then use the fact that

1/(1 - x) = SUM x^n

Hint:
The partial fractions are 1/(x - 1) - 1/(x + 2)

1/(x - 1) = -1/(1 - x)

1/(x + 2) = 1/[2(1 + x/2)] = (1/2)*1/(1 + x/2) = (1/2)*1/(1 - (-x/2))