A x y 1 Solution To show that a set is open at this level

A = [(x, y)| - 1

Solution

To show that a set is open (at this level) have to show that if you pick any point in the set, there is a neighborhood around that point so that every point in the neighborhood is in the set. You can look at the neighborhood as a little circle or square around the point at this point. Just to start you off, if your set is {x:-1