Question

If A = {1, 3, 7, 9, 10} and B = {2, 5, 7, 8, 9, 10}, then find $A\cup B$.

• A. {1, 2, 3, 4, 5, 6, 7, 8, 9, 10}
• B. {1, 2, 3, 5, 6, 7, 8, 9, 10}
• C. {1, 2, 3, 4, 5, 6, 7, 8, 9}
• D. {1, 2, 3, 5, 7, 8, 9, 10}

Answer 1

The correct option is D {1, 2, 3, 5, 7, 8, 9, 10}

Given A = {1, 3, 7, 9, 10} and B = {2, 5, 7, 8, 9, 10}
The union of two sets A and B is the set of elements which are in A, B, or in both A and B.
Here,
$A\cup B$ = {1, 3, 7, 9, 10} $\cup$ {2, 5, 7, 8, 9, 10} = {1, 2, 3, 5, 7, 8, 9, 10}
$\therefore$ $A\cup B$ = {1, 2, 3, 5, 7, 8, 9, 10}