Well...I have no idea about this question. I don't even know where to start, and I am having terrible panic on these types of proof. Can someone please explain and guide me through? Believe it or not, my textbook (which is horrible) has absolutely no examples on it, and it expects me to be able to do in the exercises after the section, this is making me feeling really deseparate... I really need some help on this topic! So if someone understands it well, please help me out! Thanks a million!