The sum of the geometric series is calculated through the equation,
Sn=a1(1−r^n)/(1−r), r≠1
First, we have to identify first if the given sequence is indeed a geometric sequence. A geometric sequence is a series of number which has a common ratio. From the given, we cannot find a common ratio when we divide the 2nd by the 1st term and the 3rd by the 2nd. Thus, this sequence is not a geometric sequence.