What is the sum of a 6–term geometric series if the first term is 6 and the last term is 966,306? :))

Question

anonymous · Answer

Just use the formula for finding the sum of n-terms.  It is :$$S _{n}=\frac{ n }{2 }(a _{1}+a _{n})$$

anonymous · Answer

You know n, you know a1, and you know an.  Soo just plug away.

jim_thompson5910 · Answer

calmat01, that formula only works for arithmetic series

not geometric series

anonymous · Answer

Oh hell, I thought something was fishy about my reply.  Arithmetic, not geometric.

anonymous · Answer

I think I deserve to be docked points.  This is getting on my nerves.

jim_thompson5910 · Answer

no it's ok

jim_thompson5910 · Answer

The first thing you need to do is solve for r in the second equation below


a(n) = a*r^(n - 1)

966306 = 6*r^(6 - 1)

tell me what you get

anonymous · Answer

You are in good hands with jim, Hopeless, let him walk you through it.  Disregard my posts.

jim_thompson5910 · Answer

no the formulas you posted are still good, just for arithmetic series only

jim_thompson5910 · Answer

anyways, what do you get when you solve 966306 = 6*r^(6 - 1) for r ?