Geometric distribution with multiple successes
"A sales representative vows to keep knocking on doors until he makes two sales. Given that his probability of success is u, let X = the number of doors he knocks on.
Find the probability mass function of X"
My thought is that x cannot be less than 2, since he would have to knock on two doors to make two sales.
I'm thinking the function would be
But when I go to find E(x), that doesn't lend itself well to the geometric form I've learned to love.
Am I on the right track at least?