DILMI, IkramFERAHTIA, Nassim: Supervisor2024-07-042024-07-042024-06https://repository.univ-msila.dz/handle/123456789/43263In this dissertation, we studied some boundary problems using variational methods, where we gave a variational formulation of this problem, then we used the Lax-Milgram theorem to demonstrate the existence and uniqueness of the solution, i.e., if we have a mathematical problem the classic formulation consists to search for a solution function of this problem.enDistributionsSobolev spacesVariational formulationLax-Milgram theoremThesis