How do you do interval notation?
Interval notation are ordered pairs that use parenthesis or brackets. Brackets are for closed intervals and parenthesis are for open intervals. For example, you have the inequality a ≤ x ≤ b. This is a closed interval notation because of the “or equal to” part of the symbol. It would be written as [a,b]. If it is a < x <b, then this is an example of an open interval notation because it does NOT have the “or equal to” part. It would be written as (a,b). Lastly, if the inequality is
a ≤ x < b, it would be written as [a,b). Always look to see if the symbol is a greater than, less than, OR greater than or equal to, and less than or equal to. All of these examples are of BOUND intervals. Next I will show some examples of UNbound intervals. The inequality x ≥ a would be written as [a,∞) because you don’t know how much x is. So therefore, it is written as infinity.