Question
The first term of a geometric series is 4 and the sum of the first three terms of the series is 64. Find the sum of the first eight terms of the series.
Answers
bobpursley
Start with the Sum of n terms first.
sum= firstterm* ((1-r^n)/(1-r))
so first term=4, and n=3, solve for r.
Now that r is known, use the formula again to solve for sum of eight terms.
sum= firstterm* ((1-r^n)/(1-r))
so first term=4, and n=3, solve for r.
Now that r is known, use the formula again to solve for sum of eight terms.