Root finding procedure?

[Thomas Hoffmann]

I am looking for octave- or matlab-code, that allows me to find the
roots of the polynomial of x that results from det(H)=0, where the Hij
are polynomials in x theirself.
E.g.: find the roots x for

       3x-4    2x+9
det (                 ) = 0
       -x+22   4x-11

I can program such a procedure myself (with successive convolution),
but this problem seems standard enough to me, that there could be a
procedure out there in octave-land. 
Any hints?

Thomas Hoffmann.