Find the arc length of the semicircle.
Either enter an exact answer in terms of it or use 3.14 for it and enter your answer as a decimal.

Let x have probability generating function gx (s) and let un generating function u(s) of the sequence uo, u1, satisfies p(x > n). show that the (1- s)u(s) = 1 - gx(s), whenever the series defining these generating functions converge.