Question

What is the sum of the geometric sequence -3, 18, -108, ... if there are 8 terms?

Answer 1

hi :)
can you find the common ratio of this sequence ?
or know what that is ?

Answer 2

Oh hey! sorry I was working on another problem! :) The common ratio of this sequence is -6

Answer 3

thats correct! :)
r = -6
a1 = 1st term = -3

use this sum formula
\(\Large S_n = a_1 \dfrac{r^n -1}{r-1}\)

Answer 4

since you need sum of 8 terms, put n = 8

Answer 5

alright give me one moment... thank you so much by the way! :)

Answer 6

So I did all of my work on paper but I got 719,835

Answer 7

yes! thats correct :)

Answer 8

Awesome! That's my final question! :) thx

Answer 9

welcome ^_^