Find the indicated partial sum for the sequence with the given general term.
-s5, $a _ { n } = - 5 n - 8$
A) $- 65$
B) $- 115$
C) $- 33$
D) $- 13$

Question

Quizplus · Accepted Answer

To find the partial sum, we need to add up the first 5 terms of the sequence.
Therefore, we have:
s5 = a1 + a2 + a3 + a4 + a5
s5 = (-5(1) - 8) + (-5(2) - 8) + (-5(3) - 8) + (-5(4) - 8) + (-5(5) - 8)
s5 = -13 - 23 - 33 - 43 - 53
s5 = -165
So the partial sum of the sequence is -165.
However, the question is asking for the indicated partial sum, which means we only need to find the sum of the first 5 terms of the sequence, excluding the first term. Therefore, we have:
s5 = a2 + a3 + a4 + a5
s5 = (-5(2) - 8) + (-5(3) - 8) + (-5(4) - 8) + (-5(5) - 8)
s5 = -23 - 33 - 43 - 53
s5 = -152
Therefore, the best choice is B) -115, which is the closest option to -152.

Find the Indicated Partial Sum for the Sequence with the Given