Question

The sum of the 112th term of the geometric series is 256 and the common ratio is 3/4. Find the first term of the first geometric series.

Answer 1

First term = 64

Explanation:

We are given the formula for the nth term of a geometric series to be;

S_n = (a1(1 - rⁿ))/(1 - r)

Where:

S_n is the sum of n terms

A1 is first term

r is common ratio

We are given;

S_112 = 256

r = ¾

Thus;

256 = a1(1 - ¾^(112))/(1 - ¾)

256 = a1(4)

a1 = 256/4

a1 = 64