Intersection of Sets
Intersection of two sets is another set with only the members that are in both sets. If the two sets do not share any common member, the intersection is the empty set with no member.
Example:
Intersection of {1,2,3} and {2,3,5} is the set {2,3}.
Intersection of the set with all primes and the set with all even numbers is the set {2} since only 2 is both even and prime.
Intersection of {1,2,3} and {4,5,6} is the empty set {}.
Remember:
Intersection contains only the common members.
Two sets are disjoint if they have no member in common, that is they have an empty intersection.
union of Sets
union of two sets is another set with all the members from both sets.
Example:
union of {2,3,5} and {1,3,4} is the set {1,2,3,4,5}.
union of {1,2,1} and {1,2} is the set {1,2,1}.
Remember:
The common members do not repeat in the union .
由于美国数学基础教育的难度增加导致数学考试越来越难，但新gre数学复习考点都是高中时候学到的知识点，考生不要过于紧张，把基本概念弄明白，再记住一些新版gre数学必备的词汇，那么相信新版gre数学应该没有问题。