Noui DjaidjaMostefa Nadir2021-03-032021-03-032020http://dspace.univ-msila.dz:8080//xmlui/handle/123456789/23987As it is known the equation A' = f with injective compact oper- ator has a unique solution for all f in the range R(A):Unfortunately, the right- hand side f is never known exactly, so we can take an approximate data f and used the perturbed problem ' + A' = f where the solution ' depends continuously on the data f ; and the bounded inverse operator ( I + A)􀀀1 approximates the unbounded operator A􀀀1 but not stable. In this work we obtain the convergence of the approximate solution of ' of the perturbed equation to the exact solution ' of initial equation provided tends to zero with p :Article