I am trying to take perform a partial fraction decomposition on the following function but something is not correct.$$Y(x)=\frac{(5x+10)(\cos x)}{x^2(x+9+i)(x+9-i)}$$ that I am trying to take the partial fraction decomposition of but something is not correct.
So far, I have $$\frac{A}{x} + \frac{B}{x^2} + \frac{C}{x+9-i} + \frac{D}{x+9+i}$$ but if I try to evaluate for $$\frac{A}{x}$$ by doing xY(x), x=0, then I get undefined. What am I missing?