Question 972657
A union B are the set of elements that are either in A or in B or in both.
A = {1,2,3,4,5,6,7,8,9}
B = {2,4,6,8}
A union B would be {1,2,3,4,5,6,7,8,9}
These are the elements that are either in A or in B or in both.
Actually, all of the elements in B are also in A.
That makes B a subset of A because all of the elements in B are also in A.
A intersect B are the set of elements that are in both A and B.
A intersect B is therefore equal to {2,4,6,8}
Those are the elements that are in both A and in B.
So, what you have here is:
A union B = A = {1,2,3,4,5,6,7,8,9}
A intersect B = {2,4,6,8}
B is a subset of A.