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#### Guest

##### Guest

I got the Probability Mass Function of the number of games they would play as:

P(X=x) = (1-p-q)^(x-1) (p+q)

I need the expectation of the number of games. So far I have:

(p+q) Summation from 1 to infinity of x (1-p-q)^(x-1)

I was told that I need to take the intergral of this to form a ore managable equation but I'm still stuck. Please help.