IKMC 2027 - Grades 11-12 - Self-study SET 1 - Thematic Batch 3 Question 9

A real function f satisfies f (1)=2 and f (x+y)=f (x)f (y) for all real x, y. Evaluate f (2)/f (1)+f (3)/f (2)+…+f (2021)/f (2020).