2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/178273In this paper we present exactly solved extended quintessence models; furthermore, through a dynamical effective Q-cosmological "constant", we recover some of the L decaying cases found in the literature. Finally we introduce a sort of complementarity between the Q-dominated or L-dominated expansions of the Universe.11 LaTeX Pages, including 4 Encapsulated Postscript Figures, submitted to Phys. Rev. LetterAstrophysicstext