2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/117699We present a general procedure to solve the equations of motion for cosmological models driven by real scalar fields with first-order differential equations. The method seems to have great power, since it works for closed, flat or open space-time, for scalar fields with both standard and tachyonic dynamics. We illustrate the procedure solving several examples which model situations of current interest to modern cosmology.RevTex, 8 pages, 3 eps figures, submitted to PLB on 08/25/2006High Energy Physics - TheoryFirst-order formalism for scalar field in cosmologytext