The answer to this question is (-∞, 0] U {3}
We use the open bracket for infinity since the graph can never reach "infinity"; however, as you decrease the value of x, the graph approaches infinity.
We use a closed bracket for 0 because the range reaches 0, but then stops.
Finally, we use the single bracket for 3 because 3 is in the range, but there is no other bounds for that part of the range.
