We use a direct variational method in order to investigate the dependence on parameterrnfor the solution of the following Du ng type equation with Dirichlet boundaryrnconditionsrnx (t) + r(t)x_ (t) À€€ Fx(t; x(t)) ð€€€ f(t) = 0rnx(0) = x(1) = 0rnand we observe that some outline of variational approach, in order to use this method.