HMMT Algebra/NT 2019/5: Next term of arithmetico-geometric sequence
Source:
February 17, 2019
HMMTalgebra
Problem Statement
Let a1,a2,… be an arithmetic sequence and b1,b2,… be a geometric sequence. Suppose that a1b1=20, a2b2=19, and a3b3=14. Find the greatest possible value of a4b4.