Question

Exercise 3.1.5: Expressing sets in set builder notation. About Express each set using set builder notation. Then if the set is finite, give its cardinality. Otherwise, indicate that the set is infinite. PLEASE show some explanation how you got answer. Thanks!

(a)

{-2, -1, 0, 1, 2}

(b)

{ 3, 6, 9, 12, .... }

(c)

{ -3, -1, 1, 3, 5, 7, 9 }

(d)

{ 0, 10, 20, 30, ...., 1000 }

Exercise 3.2.4: A subset of a power set.

(a)

Let X = {a, b, c, d}. What is { A: A ∈ P(X) and |A| = 2 }?

(b)

Let A = {1, 2, 3}. What is {X ∈ P(A): 2 ∈ X}?

Answer 1