Asked 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
Answered by PJ
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
Answered by Steve
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
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