Andy C. answered • 07/05/18

Math/Physics Tutor

The n means the number of elements in the set.

For example set A = {3,4,5,6,}.

Then n(A) = 4 because there are 4 elements in set A.

So in the given statement, A intersect B is the set whose elements

belong to BOTH set A AND set B.

Since n(A intersect B) = 0, there are NO ELEMENTS in the intersection

which means A and B are DisJoint sets, meaning they have no common elements