
geometric series


The sum of a geometric sequence, that is, a series a_{1} + a_{2} + a_{3} + ... in which the terms form a geometric sequence.
The sum of the first n terms can be obtained as follows: S_{n}  = a_{1} + a_{2} + a_{3} + ...a_{n}   = a_{1} + a_{1}r + a_{1}r^{2} + ... + a_{1}r^{n1}   = a_{1} (r^{n}  1)/(r  1) 
in which r is the common ratio.

