Question

Given these sets:

A = {1, 2, 3, 4}
B = {3, 4, 5, 6, 7}
C = {3, 5, 7, 9}

List the elements of this set
C �¿ (A u B)

Do I list the numbers in C that is not in A and B?

Answer 1

If that's (A u B), this means A union B, which is everything in both A and B, without repeating elements. When you have the upside down u, that's called intersection, and you say what the two sets have in common.