Help me define the polynomial Z(-s) for this equation

if Z(s) = 50 + j30 then what will be Z(-s) ?
can anyone please define Z(-s)
if I have a polynomial let say a(s)=ao*s+a1*s2+a2*s3.....,
then how can I write a(-s)?

Is this a trick question? You just plug in -s everywhere there was a +s before. What it means is a different question.

I asked thid question in relevence to this expression
EvenZ(s)=?[Z(s)+Z(-s)]
where Z(s)=a(s)/b(s)
if i am dealing with a lossless system
to construct the polynomial Z(-s) what to do with a(s) when say s=4GHz
should i just place -4GHz inplace of s in the polynomial Z(-s) or -j4GHz....?

I would recommend you go over to the digital signal processing board and ask that question. In the real world, yes, you would just use -4 * 2Π Grps. Think of a bandpass downconverted to baseband. It folds evenly around zero radians per second.