How many subsets does the set {9, 10} have? How do you know?
There are 2 elements in the set, so it has 2 subsets.
There are 2 elements, so it has 4 subsets (2 raised to the 2nd power)
There are 2 elements, so it has 3 subsets (2 raised to the 2nd power, minus 1)
What are the subsets of {9, 10}?
The subsets are {9} and {10}.
The subsets are {9}, {10}, {9, 10} and the empty set.
The subsets are {9}, {10}, {9,10} and {10,9}.
The subsets are {9}, {10} and the empty set.