Answer:
third option
Step-by-step explanation:
There is a common difference d between consecutive terms in the sequence, that is
d = - 13 - (- 10) = - 16 - (- 13) = - 3
This indicates the sequence is arithmetic with n th term
[tex]a_{n}[/tex] = a₁ + (n - 1)d
where a₁ is the first term and d the common difference
Here a₁ = - 10 and d = - 3, then
[tex]a_{n}[/tex] = - 10 - 3(n - 1) = - 10 - 3n + 3 = - 7 - 3n
Thus the sum of the first 6 terms is represented by
∑ - 7 - 3n ( for n = 1 to 6 )
