If 𝐴 is equal to six, five, nine, one and 𝐵 is equal to seven, five, nine, eight, what is the intersection of 𝐴 and 𝐵?
This upside-down U is a symbol for intersection. And an intersection of two sets is the set of all common elements between those sets. So what elements do 𝐴 and 𝐵 have in common?
They both have five. They both have nine. Only 𝐴 has six and one. And only 𝐵 has seven and eight. Therefore the intersection of 𝐴 and 𝐵 will be the elements five and nine.