Domain is the complete list of x-values that a function can have, and the range is the complete list of y-values that a function can have.
Domain and range can be written as (x, y) if the domain/range does not include the x or y value.
Domain/range can be written as [x, y] if the domain/range does include the x or y value.
If the function has multiple intervals, we use U to symbolize "union."
