Browse · MATH
Printjmc
algebra senior
Problem
An infinite geometric series has sum 2000. A new series, obtained by squaring each term of the original series, has sum 16 times the sum of the original series. The common ratio of the original series is , where and are relatively prime positive integers. Find .
Solution
Let be the first term and the ratio of the original series, and let . Then and . Factor to obtain . Then and imply that , so , and .
Final answer
125