Compare $ S_n = 3^n - 1 $ with the geometric sum formula. This suggests $ r = 3 $ and $ a = 2 $, since $ 3^n - 1 = 2 \cdot \frac3^n - 13 - 1 $. - AMAZONAWS

📅 March 11, 2026 👤 scraface

Mar 11, 2026

$Compare $ S_n = 3^n - 1 $ with the geometric sum formula. This suggests $ r = 3 $ and $ a = 2 $, since $ 3^n - 1 = 2 \cdot \frac{3^n - 1}{3 - 1} $.$