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
2 answers
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
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