Question

Identify the type of the following sequence:
$\sum _{i=1}^{\infty }\frac{i^3}{3^i}$

• A. Cubic GP
• B. Quadratic GP
• C. AGP
• D. AP

Answer 1

The correct option is A Cubic GP

Here, increment of $i^3$ indicates summation of cubes of natural numbers.

and $3^i$ indicates G.P. with common ratio $3$

Hence, the series is in Cubic G.P.