A, B, C and D are four sets such that A ∩ B = C ∩ D = ϕ. Consider the following: 1. A ∪ C and B ∪ D are always disjoint. 2. A ∩ C and B ∩ D are always disjoint. Which of the above statements is/are correct?
A, B, C and D are four sets such that A ∩ B = C ∩ D = ϕ. Consider the following: 1. A ∪ C and B ∪ D are always disjoint. 2. A ∩ C and B ∩ D are always disjoint. Which of the above statements is/are correct? Correct Answer 2 only
Concept:
Two sets are said to be disjoint when they have no common element.
Two sets A and B are disjoint sets if the intersection of two sets is a null set or an empty set.
A ∩ B = ϕ
Calculation:
Given: A, B, C and D are four sets such that A ∩ B = C ∩ D = ϕ
Statement 1: A ∪ C and B ∪ D are always disjoint.
⇒ (A ∪ C) ∩ (B ∪ D) = ∪
= ∪
= ∪
= (C ∩ B)] ∪ ∩
= ∩
= ∩ (∵ A ∩ ϕ = ϕ)
= (ϕ ∩ ϕ)
= ϕ
(A ∩ C) and (B ∩ D) are always disjoint.
Hence statement 2 is correct.
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Feb 20, 2025