Question

What is the sum of an 8-term geometric series if the first term is 12 and the last term is -3,359,232?

Answer 1

find the common ratio

\[r ^{7} = -3359232/12\]

then \[r = \sqrt[7]{(-339232/12)}\]

then a = 12 and n = 8 and r was found above

\[s _{n} = (a(r^n - 1)/(r -1))\]