2.( 1)∈,(2)? ,(3)∈
3.( 1){2,3,4,5}
(2){ 1,-2}
(3){0, 1,2}
4.( 1){y│y≥-4}
(2){x│x≠0}
(3){x│x≥4/5}
5.( 1)? ,? , really contained in, really contained in.
(2)∈, really contained in, really contained in, =
(3) True tolerance, true tolerance
6.A∪B={x│3≤x