SOLUTION: I can't seem to figure out how to start with this problem... The sum of the first two terms of a geometric sequence is 9. The sum to infinity of the corresponding geometric seri

Question 896823: I can't seem to figure out how to start with this problem...
The sum of the first two terms of a geometric sequence is 9. The sum to infinity of the corresponding geometric series is 12. Find all possible values of the first term and the common ratio.
Answer by rothauserc(4718) (Show Source): You can put this solution on YOUR website!
Geometric sequence is defined as
Xn = ar^(n-1)
in our case a = 6 and r = 1/2 and the geometric sequence looks like
6, 3, 3/2, 3/4, .....
the sum of a geometric sequence to infinity is defined as
a(1-r^n / 1-r)
note as n goes to infinity (1/2)^n approaches 0, then we have
6*(1/ 1/2) = 6*2 = 12

RELATED QUESTIONS
I have one last question on my homework and I can�t seem to figure it out. I�ll send the (answered by greenestamps,Theo,apshu)

Find the sum of the first 196 terms of 2,7,12,17,.. I cant seem to figure this problem... (answered by josmiceli,MathTherapy)

I am having trouble with this problem, could you please help me. 3) Use the geometric... (answered by sdmmadam@yahoo.com)

Please Help!!! I can figure out a) but not b). Can you please explain this to me? Thanks... (answered by Earlsdon)

1)Use the geometric sequence of numbers 1, 2, 4, 8,�to find the following: a) What is (answered by jim_thompson5910)

the first three terms of a geometric progression are 100,90 and 81. Find out the... (answered by Theo)

I can't seem to figure out the general term of this sequence. Could you help me out?... (answered by jim_thompson5910)

Hello, I am stuck with this problem and cannot seem to find any help. I need to find... (answered by ewatrrr)

find three consecutive integers with a sum of 204. i got for this one 68, 67, 69. is... (answered by ankor@dixie-net.com)