Question

quick maths

Answer 1

@Vocaloid

Answer 2

x; x <= -1

this implies there is a closed circle at x = -1 on the graph of x

also, the two graphs are x and -x, try to visualize what these two graphs look like

this should be enough to find the answer through process of elimination

Answer 3

hint: what do the graphs of x and -x look like?

gtg