Let A={1, 2, 3, 4} and B= {2,5,7} find the set A U B

A ∪ B is {1, 2, 3, 4, 5, 7}

Set up the union notation of set {1,2,3,4} and {2,5,7}.
{1,2,3,4}∪{2,5,7}

The union of two sets is the set of elements which are in either sets.
{1,2,3,4,5,7}