Question

Consider the set {2, 4, 6, 8}: How many subsets have exactly 2 elements?

Answer 1

given 4 elements, and choosing 2 .... hmmm

4C2 perhaps

Answer 2

it means, 4!/(4-2)!2! = 4!/(2!2!) = ..... :)

Answer 3

what does the exclamation point stand for?

Answer 4

factorial