Thread: Geometric progression

The sum of the first n elements of a geometric progression is S=(2^n)-1.
Find the first element of the progression and also prove that a(n+1)-S(n)=1.

If you can please give me an idea how to stat solving this...especially the first part.Thx

Originally Posted by nejikun

The sum of the first n elements of a geometric progression is S=(2^n)-1.
Find the first element of the progression and also prove that a(n+1)-S(n)=1.

If you can please give me an idea how to stat solving this...especially the first part.Thx

The sum of the first n elements of a GP is given by the equation. If you have only 1 element in the series it means it is the 1st element. and the sum of the first element is the element itself. So putting n=1 in the first equation will yield to the first element of the series