We use parenthesis if an interval is infinite on both boundries in order to exclude end-points .
Square brackets mean the set of all points from a to b .
If we use square brackets , it would mean we are including - infinity and + infinity , which is practically impossible .
When we , use parenthesis only the nos . lying between the two points are taken into consideration , the two points are not included .
So , we use parenthesis to exclude - infinity and + infinity .
To learn more on set notations follow link :
https://brainly.com/question/24462379
#SPJ9