# When do you use the brackets [ x, y ] and when do you use the parenthesis ( x, y) when writing the domain and range of a function in interval notation?

##### 1 Answer

Jun 20, 2018

It tells you whether the end point of the interval is included

#### Explanation:

The difference is whether the end of the interval in question includes the end value or not. If it includes it, it is called "closed", and is written with a square bracket:

An interval with both ends open or closed is called an open or closed interval. If one end is open and the other closed, then the interval is called "half-open". For example, the set