Reals

Reals represents the domain of real numbers, as in x∈Reals.

Examples

Solve over the reals:

Solve[x^2 == 2, x, Reals]
(* {{x -> -Sqrt[2]}, {x -> Sqrt[2]}} *)

Test membership:

Element[Pi, Reals]
(* True *)

Please visit the official Wolfram Language Reference for more details.