What does the expression #x in RR# mean ?

Question

Eva Adamson · Accepted Answer

A real number is any rational or irrational number.

For example: #pi, e,2, 4, -78, 1/2, 23/6# and so on

Julia Adams · Answer

It means that #x# is an element of the set of real numbers which we symbolize with #R#.

Savannah Anderson · Answer

It usually means:

"#x# is a member of the set of real numbers"
or more simply:

"#x# is a real number" #RR# usually denotes the set of Real numbers. #in# denotes membership. So #x in RR#, means that #x# is a member of the set of Real numbers. In other words, #x# is a Real number. Associated terms are: #AA x in RR" "# meaning "for all #x# in the set of real numbers". in other words: "for all real numbers #x#". #EE x in RR : ..." "# meaning "there exists a member #x# in the set of real numbers such that ..." or "there exists a real number #x# such that ...". In some kinds of constructive mathematics, where speaking of "the set of Real numbers" is considered a little presumptuous, the expression "#x in RR#" may be read as "#x# is a real number" and #AA x in RR# understood as "for any real number #x#", etc., avoiding the concept of a completed set of real numbers.

Genesis Allen · Answer

undefined In mathematical notation, "RR" typically stands for the set of real numbers. Therefore, the expression "x in RR" means that the variable "x" belongs to the set of real numbers, indicating that "x" can take on any real value.