Question 3: Let \(U=\{1,2,3,4,5,6,7,8,9,10\}\), \(A=\{2,4,6,8,10\}\), \(B=\{1,2,3,4,5\}\) and \(C=\{1,3,5,7,9\}\)
List the members of each of the following sets:
\((iii)\) \(\;\) \(A\cup B \)
Solution:
\(A\cup B =\{2,4,6,8,10\}\cup \{1,2,3,4,5\}\)
\(\ \ \ \ \ \ \ \ \ \ \ =\{1,2,3,4,5,6,8,10\}\)
Explanation:
Union \((\cup)\) means combine all elements from both sets.
No repetition — each element appears only once, even if it’s in both sets.
To find the union, don’t repeat numbers.
Use color-coding or ticks to mark used numbers.