Browse Questions

# Find the sum of 8 terms of the series whose $n^{th}$ term is given by $n^2+2^n$

$\begin{array}{1 1} 256 \\ 512 \\ 714 \\ 417 \end{array}$

Can you answer this question?

Answer : (c) 714
Explanation : $t_{n}=n^2+2^n$
$S_{n}=\frac{n(n+1)(2n+1)}{6}+\frac{2(2^n-1)}{2-1}$
$S_{8}=\frac{8(9)(17)}{6}+2(256-1)$
=714.
answered Jan 6, 2014 by