Find the complement of A intersect B (A ∩ B)'?

Question

Let A = {5, 7, 8, 9, 3, 2} B = {6, 7, 9, 10} and U be the universal set of natural numbers less than 11. Find the following. (Enter your answers as a comma-separated list. Enter EMPTY or ∅ for the empty set.)

 

(A ∩ B)' = I got {1,2,3,4,5,7,8,10} but it's wrong. Why?

Answer 1

Hello Patrick.

 

A∩B means the intersection of A and B,

or what belongs in A AND belongs in B.
For the above, A∩B = {7, 9}

 

(A∩B)', or the complement of (A∩B), means

everything that is NOT in (A∩B).

 

For the above, that would be the set of natural numbers

less than 11 except 7 and 9, or

(A∩B)' = {1, 2, 3, 4, 5, 6, 8, 10}.

 

You have 7 and you are missing 6.

 

I hope this helps.

 

Andrew M.