The graph will be a line segment with endpoints -1 and 1. Both endpoints are closed dots. This is to indicate we include the endpoints as part of the solution set. Everything between the endpoints is shaded in.
The answer in interval notation is [-1, 1]. The square brackets tell the reader to include the endpoints. This describes the interval from -1 to 1, inclusive of the endpoints.
How do we know to include the endpoints or not? By looking at the "or equal to" portion. If that is present, then we include the endpoint; otherwise, we exclude.
The original inequality
is the same as
The general rule is
turns into
for some positive number k.