(-∞; 3]U[1; +∞) = (-∞; +∞)
(-∞; 3]∩[1; +∞) = [1; 3]
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1 3
(-4; 0]U[4; 7) ={∅}
(-4; 0]∩[4; 7) = {∅}
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-4 0 4 7
[-16_3/7; 16)∪[-6; 6) = [-16_3/7; 160
[-16_3/7; 16)∩[-6; 6) = [-6; 6)
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-16_3/7 -6 6 16
(-∞; 1/2]∪(1/2; +∞) =(-∞; +∞)
(-∞; 1/2]∩(1/2; +∞) ={∅}
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