Question

What is the sum of a 7-term geometric series if the first term is 6, the last term is 24,576, and the common ratio is 4?

Answer 1

-32,766
-19,662
19,662
32,766

Answer 2

@mathmate

Answer 3

Sum of a geometric series is given by:
\[\huge S_n= \frac{a(1-r^n)}{1-r}\]
\[\huge S_7= \frac{6[(1-4)^7]}{1-4}\]
\[\huge S_7= \frac{6[-16383]}{-3}\]
\[\huge S_7= 32,766\]

Answer 4

thnx

Answer 5

Note:
\(\huge S_7=6\frac{(1-4^7)}{(1-4)}\)
The final answer is correct.