Solve[F[p]*(u-((Y[p])/p))==Y[p],Y[p]]

rce={AB[p]==(1/(1+p))*(U[p]-Y[p]),
(AB[p]-Y[p]+U[p])*(1/(1+p))==Y[p]};
Solve[rce,Y[p],AB[p]]

Solve[3+3 p+(p^2)==0]

Solve[(((Y[p]-U[p])/p)+((Y[p]-U[p])/(p+3)))*(1/p)==Y[p],Y[p]][[1]]
Print["prenos geft: ",prenos=Simplify[((Y[p]/.%)/(U[p]))]]
1.*Denominator[prenos]==0//Solve

Eigenvalues[(({{-1, 1}, {3, -2}}))]//N

Solve[{p*x1==-u-x1+x2,p*x2==2u+3x1-2x2},x2,x1]

Solve[0==-1+3 p+(p^2)]//N