on this quiz a lot of the questions have this little arch thing, example:

Find A arch thingy B
then it says
A: {2, 4, 6, 8, 10, 12}
B: {−2, −1, 2, 4, 7, 11}
can someone explain? please?

Question

on this quiz a lot of the questions have this little arch thing, example:

Find A arch thingy B
then it says
A: {2, 4, 6, 8, 10, 12}
B: {−2, −1, 2, 4, 7, 11} 
can someone explain? please?

anonymous · Answer

and on some the arch is upside down.

zepdrix · Answer

$$A \cup B$$
Like that? :o

zepdrix · Answer

that being the upside down one i assume :D hehe

anonymous · Answer

yeah!

zepdrix · Answer

$$A \cup B$$ This is the union of set A with set B.
It's asking, what elements are in either A or B?

So for our example, if
A: {2, 4, 6, 8, 10, 12}
B: {−2, −1, 2, 4, 7, 11} 
Then$$A \cup B: [−2, −1, 2, 4, 6, 7, 8, 10, 11, 12]$$
All of the elements that are in either set are included.

anonymous · Answer

wow... that's easy.
is the right side up one the same?

zepdrix · Answer

A ∩ B is the intersection of set A and set B.
It's asking, what elements do A and B share?

So for our example, if
A: {2, 4, 6, 8, 10, 12}
B: {−2, −1, 2, 4, 7, 11} 
Then
A ∩ B: {2, 4}

anonymous · Answer

omg, thank you sososo much!

zepdrix · Answer

pretty straight forward :) just have to get used to the notation.