Number Set
Posted: Wed Nov 02, 2011 12:54 pm
How many solutions has the equation A ∪ B = {1, 2, 3, 4}?
Remember: (two solutions (A1, B1) and (A2, B2) are different if and only if A1 =6 A2 or B1 =6 B2 ; for instance, A1={1, 3, 4}, B1 = {1, 2, 4} and A2 = {1, 2, 4}, B2 = {1, 3, 4} are different solutions.)
Remember: (two solutions (A1, B1) and (A2, B2) are different if and only if A1 =6 A2 or B1 =6 B2 ; for instance, A1={1, 3, 4}, B1 = {1, 2, 4} and A2 = {1, 2, 4}, B2 = {1, 3, 4} are different solutions.)