If A \ (B ∪ C) is to be written using only intersection and set difference, which form is correct?
Answer and explanation
Correct answer: (A \ B) ∩ (A \ C)
An element belongs to A \ (B ∪ C) when it is in A but not in B ∪ C. Not being in B ∪ C means that it is neither in B nor in C. Thus the element must belong simultaneously to A \ B and A \ C. Consequently, A \ (B ∪ C) = (A \ B) ∩ (A \ C). This is the set-difference form of De Morgan’s law.
Frequently asked questions
What is the correct answer to this question?
(A \ B) ∩ (A \ C)
Why is this the correct answer?
An element belongs to A \ (B ∪ C) when it is in A but not in B ∪ C. Not being in B ∪ C means that it is neither in B nor in C. Thus the element must belong simultaneously to A \ B and A \ C. Consequently, A \ (B ∪ C) = (A \ B) ∩ (A \ C). This is the set-difference form of De Morgan’s law.
Which subject and chapter does this question cover?
This is a Class 10 Mathematics question. Chapter: Sets. Topic: Operations on Sets (Union, Intersection, Difference).