how to multiply a variable with a matrix without declare it as a symbol

Hi everyone, I'm new using matlab, I just wanna know how to do this operation without declare 'Z' as a symbol.

adj(z I - G )= I*z^2+ H1*z+H 2

G,H1 and H2 are matrices

I mean, in this algorithm I can't use symbolic operations.

I would appreciate if any of you help me.

[Walter Roberson]

Is the question to find the z such that that expression holds? Would the z be a scalar or a matrix?