I came at this from the perspective of the Binomial theorem: (x + y)^n = sum{k=0,n} (n choose k) x^(n-k) y^k And since a powerset is: sum{k=0,n} (n choose k)

I came at this from the perspective of the Binomial theorem: (x + y)^n = sum{k=0,n} (n choose k) x^(n-k) y^k And since a powerset is: sum{k=0,n} (n choose k) The way we can turn the first equation into a powerset is by setting x=1 and y=1, hence: 2^n = sum{k=0,n} (n choose k)