Question

Find Sn for the given arithmetic series a1=-26 d=-9 n=24

Answer 1

- 3108

Explanation:

The sum to n terms of an arithmetic series is

`S_(n)` =
`(n)/(2)` [ 2
`a_(1)` + (n - 1)d ]

Substitute the given values into the formula

`S_(24)` =
`(24)/(2)` [ (2 × - 26) + (23 × - 9) ]

= 12 ( - 52 - 207 )

= 12 × - 259 = - 3108