Find mu (mean); E [X (X - 1)] and sigma squared (variance) for each of the following distributions:

1. f (x) = (1 / x! ) (1/2)^5 (5! / (5 - x)! ) ; for x = 0, 1, 2, 3, 4, 5

2. f (x) = (e^ -a) (a^x)/(x!) for x = 0, 1, 2,... (a > 0)

any help will be very much appreciated I'm so lost on this homework question.