Question

the nth term of the series whose sum to n terms is 5n2 + 2n is

Answer 1

Answer:

The nth term of the series is 10n-3.

Step-by-step explanation:

It is given that the sum of n terms is

$S_n=5n^2+2n$

$S_{n-1}=5(n-1)^2+2(n-1)=5(n^2-2n+1)+2n-2=5n^2-10n+5+2n-2=5n^2-8n+3$

We now that

$a_n=S_n-S_{n-1}$

$a_n=5n^2+2n-(5n^2-8n+3)$

$a_n=5n^2+2n-5n^2+8n-3$

$a_n=10n-3$

Therefore the nth term of the series is 10n-3.

Answer 2

Answer:

nth term of the series is 10n-3.