(−∞,1]∪[2,∞)(-\infty, 1] \cup[2, \infty)(−∞,1]∪[2,∞)
(−∞,1)∪(2,∞)(-\infty, 1) \cup(2, \infty)(−∞,1)∪(2,∞)
(−∞,1]∪(2,∞)(-\infty, 1] \cup(2, \infty)(−∞,1]∪(2,∞)
(−∞,1)∪[2,∞)(-\infty, 1) \cup[2, \infty)(−∞,1)∪[2,∞)