(a) A = {1, 3}; B = {1, 4}. A and B have different elements,
∴ A ≠ B.
(b) A = {x: x + 2 = 2} = {0}; B = {0}. A and B have same elements,
∴ A = B.
(c) A = {1, 3, 4, 4} = {1, 3, 4}; B = {3, 1, 4}. A and B have same elements,
∴ A = B.
(d) A = { 1,1/2,1/3, ................ } ;
B = {1/n : n ε N} = { 1/1,1/2,1/3,...} .
A and B have same elements, ∴ A = B.
