2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/129680We show that there is significant cancellation in certain exponential sums over small multiplicative subgroups of finite fields, giving an exposition of the arguments by Bourgain and Chang.15 pages. To appear in Proceedings of CRM-Clay workshop on Additive Combinatorics, Montreal 2006Number Theory11L07, 11T23text