FUNCTION 11..HELP!
posted by Anonymous .
The sun of the first five terms of a geometric series is 186 and the sum of the first six terms is 378. if the fourth term is 48, determine a,r, t10, S10

The sun of the first five terms of a geometric series is 186 and the sum of the first six terms is 378. if the fourth term is 48, determine a,r, t10, S10

Since S6 = S5 + T6,
378 = 186 + T6
T6 = 192
T6 = T4*r^2
192 = 48r^2
r^2=4
r=2
T4 = ar^3
48 = 8a
a = 6
Sequence is thus
6, 12, 24, 48, 96, 192, ...
T10 = 6*2^9 = 3072
S10 = 6*(1023) = 6138