The question is:
The sum of the first term and the second term of a geometric series is equal to twice the sum of the second term and third term of the series.
a] given that the common ratio is positive, find the value of the common ratio.
b] the sum to infinity of the series is 12. find, correct to two decimal places, the sum of the first eight terms of the series.
I will be able to do the part' b] OK, but the first part is troubling and I find it complicated.
I see that u1 + u2 = 2 (u2 + u3)
So [ u1 =
, u2 =
] = 2 x [ u2 =
, u3 =
] ...{I think}
What happens from here?
Please could someone help?