Question

The fourth term of the sequence, whose sum of n terms is given by (-1)-1 n(n-1) is


{Correct answer will be marked branliest and the wrong one will be reported}​

Answer 1

Given:

The sum of n terms is given by (-1)-1 n(n-1) is

To find:

The fourth term of the sequence is?

Solution:

From given, we have,

The sum of n terms is given by (-1)-1 n(n-1) is

Sn = (-1) -1 × n(n - 1)  = 1 × n(n - 1)  = n(n - 1)

S1 = (-1) -1 × 1(1 - 1) = 0

t1 = 0

S2 = (-1) -1 × 2(2 - 1) = 1 × 2

t2 = 2 - 0 = 2

S3 = (-1) -1 × 3(3 - 1) = 1 × 6 = 6

t3 = 6 - 2 = 4

S4 =  (-1) -1 × 4(4 - 1) = 1 × 12 = 12

t4 = 12 - 6 = 6

Therefore, the fourth term of the sequence is 6