Universal sets?

Question

For the universal set U - {0,1,2,3,4,5,6,7} and the sets A= {1,5}, B = {1,2,3,4} and C={4,6}, list the elements in the following sets.

a. A "union" <-- ( should be an upside down U shape) B
b. A U B'
c. A (upside down U) (B U C)

Answer 1

The upside down U, ∩, is called intersect. The intersection of two sets consists of the elements that are common to both sets.

a) A ∩ B = {1, 5} ∩ {1, 2, 3, 4} = {1} [Only the 1 is a member of both A and B]

b) A U B' = {1, 5} U {5, 6, 7} = {1, 5, 6, 7}

c) A ∩ (B U C) = A ∩ {1, 2, 3, 4, 6} = {1,5} ∩ {1, 2, 3, 4, 6} = {1}