Question

I don’t understand the symbols in number 5 please

Answer 1

Binary Operations

The union of two sets A and B is denoted A ∪ B and

is defined as A ∪ B = {x|x ∈ A or x ∈ B}.

The intersection of two sets A and B is denoted A∩B

and is defined as A ∩ B = {x|x ∈ A and x ∈ B}.

Two sets are disjoint if they have no elements in common,

that is, A and B are disjoint if A ∩ B = ∅.