Geometric progression has 6 terms. If the 3rd and 4th term are 28-and 56 find the first term

Answer 1

Let's denote the first term of the geometric progression as a and the common ratio as r.

Since the 3rd term is 28, we have:
a * r^2 = 28 ...(1)

Since the 4th term is 56, we have:
a * r^3 = 56 ...(2)

Dividing equation (2) by equation (1), we get:

(a * r^3) / (a * r^2) = 56 / 28
r = 2

Substituting this value of r into equation (1), we have:
a * (2^2) = 28
a * 4 = 28
a = 28 / 4
a = 7

Therefore, the first term of the geometric progression is 7.