the common ratio of a geometric series is 3 and the sum of the first 8 terms is 3280. what is the first term of the series?
1 answer:
Answer: 1
Step-by-step explanation:
The formula for calculating the sum of a Geometric series if the common ratio is greater than 1 is given as :
=
Where is the sum of terms , a is the first term , r is the common ratio and n is the number of terms.
From the question:
= 3280
a = ?
r = 3
n = 8
Substituting this into the formula , we have
3280 =
3280 =
Multiply through by 2 , we have
6560 = a ( 6560)
divide through by 6560, we have
6560/6560 = a(6560)/6560
Therefore : a = 1
The first term of the series is thus 1
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