If \(A=\{3,6,9\}\) and \(B=\{9,12,15\}\), which element must belong to \(A\cup B\)?
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Answer and explanation
Correct answer: 6
The union \(A\cup B\) contains every element that belongs to at least one of the two sets. Since 6 is an element of \(A\), it must be included in the union. In fact, \(A\cup B=\{3,6,9,12,15\}\). The numbers 18, 21, and 0 are not present in either set, so they cannot belong to the union.
Frequently asked questions
What is the correct answer to this question?
6
Why is this the correct answer?
The union \(A\cup B\) contains every element that belongs to at least one of the two sets. Since 6 is an element of \(A\), it must be included in the union. In fact, \(A\cup B=\{3,6,9,12,15\}\). The numbers 18, 21, and 0 are not present in either set, so they cannot belong to the union.
Which subject and chapter does this question cover?
This is a Class 10 Mathematics question. Chapter: Sets. Topic: Operations on Sets (Union, Intersection, Difference).
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