6. The sets A and B are defined as: A = {2, 5, 7} B = {*, +} (a) Express the set A x B in roster notation. (b) Give an example of an element in A × B × B × B. (c) Give an example of an element in B3. (d) What is A × Ø.

Let the domain be the set of all people. Let: P(x,y): x knows y. Which of the following is the correct translation for: "Someone is known by everyone."   Select the correct option (a) ∃y∀x P(x,y) (b) ∃x∀y P(x,y) (c) ∀y∃x P(x,y) (d) ∀x∃y P(x,y)

Use the roster method to describe the elements of the following sets. ([–4, 6] n (−3, 11)) nZ = ([−4, –3) U (−3, 6)) nZ =