each element of set X has three choices ,
1 : go to set Y
2 : go to set Z
3 : go to neither
thus for 5 elements of X , number of ways = 35
Let X = {1, 2, 3, 4, 5}. The number of different ordered pairs (Y, Z) that can formed such that Ysubset X, Z subset X and Y∩Z is empty, is?
each element of set X has three choices ,
1 : go to set Y
2 : go to set Z
3 : go to neither
thus for 5 elements of X , number of ways = 35