# Partial fraction decomposition with cos() in the numerator

1. Mar 23, 2017

### Mr Davis 97

1. The problem statement, all variables and given/known data
See below

2. Relevant equations

3. The attempt at a solution
I am looking at a particular integral, and to get started, my text gives the indication that one should use partial fraction decomposition with $\displaystyle \frac{\cos (ax)}{b^2 - x^2}$. Specifically, it says "then make a partial fraction expansion." However, I only learned the technique of partial fraction decomposition in the context of polynomials. I am not sure exactly what it is asking me to do.

2. Mar 23, 2017

### vela

Staff Emeritus
It just means to expand the $\frac{1}{b^2-x^2}$ part. The resulting factors will still be multiplied by the cosine.