Question

Please explain me about close and open interval.

Answer 1

open interval is an interval, which does not contain its end point (or limit points) denoted by (x,y) i.e. it has all points between x and y but not x and y

close interval is an interval, which contains all of its points including its limit points, denoted by [x,y] i.e. it has all points between x and y + points x and y