use the formula to evaluate the series 2 - 10 + 50 -250 + ... a6
sn = a1(1-r^n) / 1-r

Question

use the formula to evaluate the series 2 - 10 + 50 -250 + ... a6  
sn = a1(1-r^n) / 1-r

anonymous · Answer

geometric series I need help

ghostgate · Answer

So you're trying to find what 'a6' is, correct?

anonymous · Answer

the question doesn't specifically say that, so im not sure all it really says is to evaluate the series using that formula

ghostgate · Answer

Well I think I understand the 'rate' I believe it would be called, if I'm reading this correctly your number list is:
2, -10, 50, -250, ... a6
Well, you're 'rate' is -5, that's for sure if that's the case.
Whether you use the formula or not you'll come up with this answer:
a6 = -6,250
I hope this helps in someway!
{---Ghostgate---}
If you need help understanding how to use the formula, then message me and I'll bring up my notes.

anonymous · Answer

I tried that answer and it came out incorrect, I don't really know why :/

ghostgate · Answer

Well alternatively I came out with 2,603.8, I don't suppose that's the answer they were looking for... hold on, I'll try to bring my notes and try to figure out their equation.

anonymous · Answer

thankyou I appreciate it

ghostgate · Answer

No problem, too bad I couldn't perhaps know what I was doing so I would have been positive over my answer, that way I could have went over the steps to complete it.

anonymous · Answer

its totally fine(: