SOLUTION: The sum of the first two terms of an exponential sequence is 135 and the sum of the third and the fourth terms is 60. Given that the common ratio is positive, calculate the common
Algebra ->
Sequences-and-series
-> SOLUTION: The sum of the first two terms of an exponential sequence is 135 and the sum of the third and the fourth terms is 60. Given that the common ratio is positive, calculate the common
Log On
Question 846732: The sum of the first two terms of an exponential sequence is 135 and the sum of the third and the fourth terms is 60. Given that the common ratio is positive, calculate the common ratio and d first term Answer by richwmiller(17219) (Show Source):
You can put this solution on YOUR website! Tn = t * r^(n - 1)
T2 = t * r
T2+T1=135
t*r+t=135
T3 = t * r^2
T4 = t * r^3
T3+T4=60
t*r^2+t*r^3=60,
(r^3+r^2)t = 60
t*r+t=135
(r+1)*t = 135
(r^3+r^2)t = 60
(r+1)*t = 135
r = 2/3, t1 = 81
