Question:In the first homework, there are relations in space which do not involve the z variable. Does this define an object in the plane? | Answer: |
Question:No, in problem 1, all sets are sets in space. If you take for example the set x^{2}2 + z^{2} = 1, then the y variable is not involved. So, we can chose y arbitrarily. The equation defines a cylinder in space. | Answer: Is it ok to use an older edition of a textbook. |