Question:

The sum of the first 20 terms of the series $5+11+19+29+41+\ldots$ is

3520

3450

3250

3420

Step-by-Step Solution

Key Concept: Find $T_n$ by method of differences: $T_n=n^2+3n+1$. Sum $S_{20}=\sum_{n=1}^{20}(n^2+3n+1)$.

$S_{20}=3520$.

Correct Answer: 1