Question:
Which of the following sets are equal?
A = {x : x ∈ N, x, < 3},
B = {1, 2}
C = {3, 1}
D = {x : x ∈ N, x is odd, x < 5},
E = {1, 2, 1, 1} F = {1, 1, 3}.
Solution:
A = {1, 2}
B = {1, 2}
C = {3, 1}
D = {1, 3}
E = {1, 2, 1, 1} = {1, 2}
F = {1, 1, 3} = {1, 3}
∴ A = B = E and C = D = F