Worked example 1 If A = {1, 2, 3} and B = {3, 4, 5}, 핌 = {1, 2, 3, 4, 5, 6, 7, 9} (i) Find A\B
(ii) Find B\A Solution
Set diff erence is not commutative. A\B is not equal to B\A
1 2
핌 The complement of a set
The complement of a set A is the set of all elements in the universal set that are not in A. The symbol A’ (or sometimes Ac complement of a set.
) is used to denote the Worked example 2
At a farmers’ market, 50 people were asked if they like strawberries or blueberries or both. 30 people like strawberries, 40 people like blueberries and 21 people like both.
(i) Draw a Venn diagram to represent this information. (ii) Find the number of people who did not like blueberries. (iii) Find the number of people who did not like strawberries.