MathDB
Geometric Series Equations

Source: 2016 AIME I #1

March 4, 2016
2016 AIME IAIMEgeometric series

Problem Statement

For 1<r<1-1 < r < 1, let S(r)S(r) denote the sum of the geometric series 12+12r+12r2+12r3+.12 + 12r + 12r^2 + 12r^3 + \ldots. Let aa between 1-1 and 11 satisfy S(a)S(a)=2016S(a)S(-a)=2016. Find S(a)+S(a)S(a) + S(-a).