Question

what is the difference between a open and closed circle

Answer 1

on a number line ? do you mean filled in versus empty ?

Answer 2

on a number line

Answer 3

say you have
x≥0 (notice the line underneath the >)
that says: x is greater than *or equal* to 0
in other words, x is 0 or bigger.
on a number line, you used a solid, filled in circle at 0 to show 0 is part of the answer.

if you have
x>0
that says that x is bigger than 0.... x can be *very, very, very* close to 0, but always bigger than 0. To show this, we use an open circle at 0

in both cases, we draw an arrow to show what x values could be