# Question:Do you know what the poles/singularities of this expression are? How do I find them?

## Question:Do you know what the poles/singularities of this expression are? How do I find them?

> I would like to integrate the following expression that I call s2

> s2 := (1/2/Pi+2*Q*u/(1+u^2))^2/((1+beta^2*(1/2/Pi+2*Q*u/(1+u^2))^2)*(1+u^2));

using the residue theorem. To do this I first want to find the roots (poles) of the expression. I do this by solving for the denominator equal to zero as below.

> s3:=(1+beta^2*(1/2/Pi+2*Q*u/(1+u^2))^2)*(1+u^2);

> s4:= solve(s3=0,u);

but I then get the RootOf expression which I can't interpret. Are the poles/singularities of s2 somehow tractable from s4 - the root of expression? If not how do I get the poles of s2 or otherwise calculate the residues? I am really interested in getting the residues but only if this can't be done then I would appreciate any advice as to alternative ways of evaluating the integral of s2 for u = -infinity..infinity.

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