Answers

2016-04-12T05:06:09+05:30
The union:
x ∈ B U C (x is an element of B U C) ⇔  x ∈ B  or  x ∈ C  ⇔  x ∈ B  ∨  x ∈ C

Absolute complement of the union:
x ∈ (B U C)'   ⇔  x ∉  B U C  ⇔  x ∉ B and  x ∉ C ⇔  x ∉ B  ∧  x ∉ C

x ∈ (A U B U C)'  ⇔  x ∉ A U B U C  ⇔ x ∉ A  ∧  x ∉ B  ∧  x ∉ C
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