In interval notation, all real numbers are expressed as the interval from negative infinity to positive infinity. This is written as:
(−∞, ∞)
This notation indicates that there are no restrictions on the set of real numbers, meaning it includes every possible real number, from negative values all the way up to positive values without any gaps. The parentheses around the infinity symbols represent that these endpoints are not included, which aligns with the idea that we’re considering all real numbers, including those that extend infinitely in both directions.