Question

If the sum of '$n$' terms of an A.P. is $2n^2+5n$, then find its $n^{th}$ terms.

• A. $5n+2$
• B. $4n+3$
• C. $4n-1$
• D. $5n-3$

Answer 1

Answer: (B)

$4n+3$

Let $t_n$ is the n th term of sequence so $t_n=s_n-s_{n-1}$
$\Rightarrow 2n^2+5n-2(n-1{)}^2-5(n-1)$
$\Rightarrow 2n^2+5n-2n^2+4n-2-5n+5$
$\Rightarrow 4n+3$