For a piecefunction, consider that the black points are the specific values of the function, where there are also blank points.
Then, you can conclude:
f(-2) = 1
f(1) = -2 (here you consider only the black point)
f(x) = 0
in this case, consider the values of x where the curve crosses the x-axis,
the function is equal to 0 when x = -3 and x = 4
