weird...I could have sworn I already replied to you. I'm studying Computer Engineering at George Washington U. Unlike you, I'm not smart and am doing it part time so I can continue working. my wife is having a good time with it; always asking me questions like, "I thought you got a STEM degree so you wouldn't have to work two jobs?" :). I'll look you up on linked

thanks a lot. not sure if I mentioned it or not, but these are the last couple of practice questions I was trying to bang out for my PhD prelims. if I actually pass, you'll definitely get a "thanks" in my dissertation. :)

ahh, now I've got it. thanks.

Thanks. Those videos really helped me with your explanation. so now I have another question. if I now have H(z) = 1 - 0.9z^-1, how do I find the poles so I can get the ROC? it's getting late and my brain may be shutting down, but I can't figure which algebra tricks will get me there.