Question

What is the sum of the first 11 terms in the arithmetic sequence if the first term is -3 and the common difference d is 5.  

a.
152


b.
352


c.
402


d.
242​

Answer 1

d

Explanation:

The sum to n terms of an arithmetic sequence is

`S_(n)` =
`(n)/(2)` [ 2a₁ + (n - 1)d

where a₁ is the first term and d the common difference

Here a₁ = - 3 and d = 5, thus

`S_(11)` =
`(11)/(2)` [ (2 × - 3) + (10 × 5) ]

= 5.5(- 6 + 50)

= 5.5 × 44

= 242 → d

Answer 2

d. 242..................