The graph of a linear function is shown
below. What is the domain of the
function?

Answer:
{ x | -3 <= x < +1 }
Step-by-step explanation:
We note that the graph occupies from x=-3 to x=+1, while -3 is a value included (endpoint is solid), and +1 is excluded (endpoint hollow).
Thus the domain is { x | -3 <= x < +1 }