For all x values before 0, the function f(x) = -2
For all values after or equal to 0, the function f(x) = 3.
In the picture, the open circle means the graph does not exist there. The filled in circle means the graph does exist there. The condition for f(x) to equal -2 is for x to be LESS than 0, not equal to 0 so we use the open circle.
