Who ever gave you this problem expects you to know what a "geometric series" is! A geometric series (actually it is NOT a "series" it is a "sequence") is of the form a, ar, ar^2, ar^3, ar^4, etc. The first term is "a" and we are told that is 3 in this problem. So the fourth term is S4= 3r^3 and the eighth term is S8= 3r^7. We are told that their ratio is 1/17. So S4/S8= 3r^3/3r^7= 1/r^4= 1/17.
What is r? And then what are the first three terms of the sequence.
