Find a geometric series of 3 or more positive integers, starting with 1, such that its sum is a perfect square.
See if you can find another such series.
The sum of the first n terms of a geometric series is:
Sn = t1(1-r^n)/(1-r)
is the first term and r is the common ratio (and not 0).
Since this problem specifies that t1=1
, we need to find a solution for
Sn = (1-r^n)/(1-r) = x²
where x, r, and n are all integers.
I haven't time to complete it now (back to work!), but that is where I think we need to start.
Posted by DJ
on 2003-07-14 06:43:22