Question: factoring a polynomial with irrational roots

Hi everybody:

I am having problems with the expression shown below.

X[1](s) = (s^2+2)*s/(1+s^4+3*s^2);

Specifically, when I try to find the inverse of the Laplace transform I get

x[1](t) = (1/10)*(sum((_alpha^2+4)*exp(_alpha*t), _alpha = RootOf(1+_Z^4+3*_Z^2)));

which obviously is not what I am looking for. Realizing that the problem must be the denominator I try to factor it using the factor command. That does not work either. If I do the factoring myself, that is

X[1] := (s^2+2)*s/((s^2+(1/4)*(sqrt(5)-1)^2)*(s^2+(1/4)*(sqrt(5)+1)^2));

then there is no problem with the Laplace inversion. Tech support tells me the culprit are the square roots. Unfortunately, I cannot find not even a simple mention under help?

Anyone cares to commend/suggest a workaround.

thanks a lot Dimitrios

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