Consider the sequence ana_nan where an=n⋅2−na_n = n \cdot 2^{-n}an=n⋅2−n. Is this a geometric sequence?
Yes, common ratio r=0.5r = 0.5r=0.5
No, it is an arithmetico-geometric sequence
Yes, common ratio r=2r = 2r=2
No, it is purely arithmetic