Find the indicated sum.
-$a _ { 1 } = - 5 , r = 2 ; \text { find } \mathrm { s } _ { 14 }$
A)-81,935
B)-81,913
C)-81,915
D)-81,878

Question

Quizplus · Accepted Answer

The sum of a geometric series can be found using the formula $s_n = a_1 \frac{1 - r^n}{1 - r}$, where $s_n$ is the sum of the first $n$ terms, $a_1$ is the first term, $r$ is the common ratio, and $n$ is the number of terms. Here, $a_1 = -5$, $r = 2$, and $n = 14$. Plugging these values into the formula gives $s_{14} = -5 \frac{1 - 2^{14}}{1 - 2} = -5 \frac{1 - 16384}{-1} = -5(-16383) = 81915$.

Find the Indicated Sum a1=−5,r=2; find s14a _ { 1 } = - 5 , r = 2 ; \text { find } \mathrm { s } _ { 14 }a1​=−5,r=2; find s14​

Find the Indicated Sum $a _ { 1 } = - 5 , r = 2 ; \text { find } \mathrm { s } _ { 14 }$