3. Try the following questions: (i) show that a closed interval is a closed set; (ii) show that the set of integers Z is a closed set; (iii) based on your proof of part (i), find an unbounded set that...

Extracted text: 3. Try the following questions: (i) show that a closed interval is a closed set; (ii) show that the set of integers Z is a closed set; (iii) based on your proof of part (i), find an unbounded set that has no limit point. I have done part (i) in class, I put it here to make sure that you understand my proof. Make sure that eventually you can prove it without looking at my proof.