Calculate the sum of the finite geometric series $\sum_{n-1}^{8}4(3)^{n-1}$. You can use Des

Question

Calculate the sum of the finite geometric series $\sum_{n-1}^{8}4(3)^{n-1}$. You can use Desmos.

. A. 8,748. B. 13,121. C. 13,120. D. 4,372.

GPT-5 mini · Answer

Interpret the sum as ∑_{n=1}^{8} 4·3^{n-1}. This is a geometric series with a = 4, r = 3, and n = 8.

S = a(1 − r^n)/(1 − r) = 4(1 − 3^8)/(1 − 3)
3^8 = 6561, so S = 4(1 − 6561)/(−2) = 4(6560)/2 = 4·3280 = 13,120.

Answer: C.

<p>Calculate the sum of the finite geometric series <span>\(\sum_{n-1}^{8}4(3)^{n-1}\)</span>. You can use Desmos. </p><p></p>. A. 8,748. B. 13,121. C. 13,120. D. 4,372.