Find the indicated partial sum for the sequence with the given general term
-$s_{4}, a_{n}=(-1)^{n}$
A) 1
B) 0
C) -4
D) -1

Question

Quizplus · Accepted Answer

The sequence generated by $a_{n}=(-1)^{n}$ alternates between positive and negative values starting with $n=1$. For the first four terms, we have: $a_{1}=(-1)^{1}=-1$, $a_{2}=(-1)^{2}=1$, $a_{3}=(-1)^{3}=-1$, and $a_{4}=(-1)^{4}=1$. Adding these together, $s_{4} = -1 + 1 - 1 + 1 = 0$.

Find the Indicated Partial Sum for the Sequence with the Given