$ 120 = \fracn2(2×4 + (n−1)×4) = \fracn2(8 + 4n − 4) = \fracn2(4n + 4) = 2n(n + 1) $ - AMAZONAWS

📅 March 11, 2026 👤 scraface

Mar 11, 2026

$120 = \frac{n}{2}(2×4 + (n−1)×4) = \frac{n}{2}(8 + 4n − 4) = \frac{n}{2}(4n + 4) = 2n(n + 1)$