The sum of the First n terms of a linear sequence is ce is 2 - 7 {n}^(2) , find the second term​

Question

The sum of the

First n terms of a linear
sequence is
ce is

`2 - 7 {n}^(2)`
, find the second term​

Answer 1

-21

Explanation:

Given the sum of the first n term as;

Sn = 2 - 7n^2

The nth term is expressed as;

Tn = Sn - Sn-1

Sn-1 = 2 - 7(n-1)^2

Tn = 2 - 7n^2 - (2 - 7(n-1)^2)

Tn = -7n^2 + 7(n-1)^2

To get the second term, we will substitute n = 2 into the resulting expression

T2 = -7(2)^2 + 7(2-1)^2

T2 = -7(4)+7(1)^2

T2 = -28 + 7

T2 = -21

Hence the second term of the sequence is -21