Question

what is the sum of the geometric sequence -3,18,-108.. if there is 7 term?

Answer 1

a=first term=-3 ,r=common ratio=-6 ,n=number of all terms=7 .
Use the Rule :
\[\huge \rightarrow Sn=\frac{a(1-r^n)}{1-r}\]

Answer 2

okay.... now what?

Answer 3

Now substitute instead of each variable its number as i listed to u

Answer 4

so whats the answer?

Answer 5

u can evaluate it :D
Don't u have a calculator ?

Answer 6

no :(

Answer 7

ok, http://www.online-calculator.com/ :D

Answer 8

please, please help. im on my last test in the whole class.

Answer 9

please give me the answer, i dont normally ask for answers but i have about 20 minutes left until i get kicked out of the test and i wont be able to graduate if i dont finish up.

Answer 10

Ok
The final answer is :119973

Answer 11

isnt it a negative?

Answer 12

Sry ,your are right ..
Its -119973

Answer 13

thanks :)

Answer 14

Good Luck with your test.