Question:
Let A = {3, 6, 12, 15, 18, 21}, B = {4, 8, 12, 16, 20}, C = {2, 4, 6, 8, 10, 12, 14, 16} and D = {5, 10, 15, 20}. Find:
(i) $A-B$
(ii) $A-C$
(iii) $A-D$
(iv) $B-A$
(v) $C-A$
(vi) $D-A$
(vii) $B-C$
(viii) $B-D$
Solution:
Given:
A = {3, 6, 12, 15, 18, 21}, B = {4, 8, 12, 16, 20}, C = {2, 4, 6, 8, 10, 12, 14, 16} and D = {5, 10, 15, 20}
(i) $A-B=\{3,6,15,18,21\}$
(ii) $A-C=\{3,15,18,21\}$
(iii) $A-D=\{3,6,12,18,21\}$
(iv) $B-A=\{4,8,16,20\}$
(v) $C-A=\{2,4,8,10,14,16\}$
(vi) $D-A=\{5,10,20\}$
(vii) $B-C=\{20\}$
(viii) $B-D=\{4,8,12,16\}$