From the graph, the lowest possible value of x is gotten from the point to the left of the graph and the highest point is that to the right of the graph.
Tracing the point to the left of the graph to the x-axis, we have that x = -3
Tracing the point to the right of the graph to the x-axis, we have that x = 4
Therefore, the lowest possible value of x is -3 and the highest possible value is 4.