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**[SOLVED] how many elements are in two power sets**

**1. Homework Statement**

a.How many elements are in the power set {1,2,3,4}? b.How many elements are in the power set {1,2,3,4,5}?

**2. Homework Equations**

**3. The Attempt at a Solution**

a. {empty set, {1}, {2}, {3}, {4}, {1,2}, {1,3}, {1,4}, {2,3}, {2,4}, {3,4}, {1,2,3}, {1,2,3,4}} Are there 13 elements?

b. {empty set, {1}, {2}, {3}, {4}, {5}, {1,2}, {1,3}, {1,4}, {1,5}, {2,3}, {2,4}, {2,5}, {3,4}, {3,5}, {4,5}, {1,2,3}, {1,2,3,4}}

Are there 19 elements?

Is there a general rule as to how many elements are in a power set?

Thank you very much