Question

What is the intersection of yhe sets A={2,3,5,7,11}and B={5,11,13,15,17}?

Answer 1

The intersection of two sets A and B is defined as the set composed by the elements appearing in both A and B.

So, the intersection is

$A\cap B = \{5,11\}$

Because all the other numbers do not belong to both sets:

• 2, 3 and 7 belong to A alone
• 13, 15 and 17 belong to B alone
• 5 and 11 belong to both A and B