My professor introduced to us this concept, but when she was explaining it, I don't think she even knows what she is talking about. So I've come to ask people who know their stuff to help. I was told that on R2, the inequalities (1) [tex]x > 0, y > 0[/tex] Is open and unbounded (2) [tex]x \geq 0, y \geq 0[/tex] Is closed and unbounded But this doesn't make sense to me. how could this be closed and unbounded? Clearly, x and y will never reach any finite value. A boundary region is which one that doesn't stretch to infinity in anyway, but a closed region is one where it contains it boundary. [tex]x \geq 0, y \geq 0[/tex] goes to infinity, so it isn't bounded, but how does this "contain" infinity?