An Arithmetic Geometric sequence
Problem 235Published on Saturday, 7th March 2009, 05:00 am; Solved by 3626; Difficulty rating: 40%
Given is the arithmetic-geometric sequence u(k) = (900-3k)rk-1.
Let s(n) = Σk=1...nu(k).
Find the value of r for which s(5000) = -600,000,000,000.
Give your answer rounded to 12 places behind the decimal point.