All we care about is what happens at, or near
x =-1x=−1
ff is constant (its value doesn't change) near x = -1x=−1
No matter if we approach -1−1 from the left or the right, ff remains constant at f(x) = 1f(x)=1
Since ff is also defined at that point, it holds that both one-sided limits (questions a,b) exist, are real numbers, and equal to 11, so the general limit (two sided limit, question c) also exists and is 11. Finally, judging from the graph, f(-1)f(−1) is clearly defined, and equal to 11 (question d).
