Find the sum of the first n terms of the following arithmetic sequence.
-$$a _ { 1 } = - 12 , d = 4 ; \quad n = 5$$
A) $- 48$
B) $- 20$
C) $- 60$
D) 8

Question

Quizplus · Accepted Answer

The sum of the first n terms of an arithmetic sequence can be found using the formula $S_n = \frac{n}{2} [2a_1 + (n - 1)d]$, where $S_n$ is the sum of the first n terms, $a_1$ is the first term, $d$ is the common difference, and $n$ is the number of terms. Plugging in the given values: $S_5 = \frac{5}{2} [2(-12) + (5 - 1)4] = \frac{5}{2} [-24 + 16] = \frac{5}{2} [-8] = -20$.

Find the Sum of the First N Terms of the Following