No. It won't look like that. fminunc cannot somehow magically know how you intend the inputs to be used. Computers cannot read your mind. Well, not yet, but the mind reading toolbox is still under beta test.
Functions assume the input paraneters are as they are defined in the help.
If you want to optimize both A and x, then you need to treat all parameters in one vector (or array). Split them apart inside your objective function.