The Lagrange-Charpit method

We give a rigorous description of the Lagrange-Charpit method used to find a complete integral of a nonlinear p.d.e. adapted for a university course in differential equations

On the uniqueness of positive solution of an elliptic equation

This work deals with the uniqueness of positive solution for an elliptic equation whose nonlinearity satisfies an specific monotony property. In order to prove the main result, we employ a change of variable used in previous papers and the maximum principle.Ministerio de Ciencia y Tecnologí