(−∞,−2]∪[2,∞)(-\infty,-2] \cup[2, \infty)(−∞,−2]∪[2,∞)
(−∞,−2)∪(2,∞)(-\infty,-2) \cup(2, \infty)(−∞,−2)∪(2,∞)
[−2,2][-2,2][−2,2]
(−2,2)(-2,2)(−2,2)