Question

What is the sum of a 6-term geometric sequence if the first term is 11, the last term is -11,264 and the common ratio is -4?

Answer 1

S6 = 11 * (1 - (-4)^6)
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1 - (-4)

Answer 2

you don't need to use the last term

Answer 3

\(\bf S_n =a_1\left(\cfrac{1-r^n}{1-r}\right)\\
a_1 = \text{first term}\\
\text{r = ratio}\\
n = n^{th}\text{ term}\)

Answer 4

read cwrw238 above