RT journal article T1 λ-Symmetries and integrability by quadratures A1 Muriel Patino, María Concepción A1 Romero Romero, Juan Luis A1 Ruiz Serván, Adrián A2 Matemáticas K1 λ−symmetries K1 first integrals K1 integrating factors K1 Jacobi last multiplier AB It is investigated how two (standard or generalized) λ-symmetries of a given second-order ordinary differential equation can be used to solve the equation by quadratures. The method is based on the construction of two commuting generalized symmetries for this equation by using both λ-symmetries. The functions used in that construction are related with integrating factors of the reduced and auxiliary equations associated to the λ-symmetries. These functions can also be used to derive a Jacobi last multiplier and two integrating factors for the given equation. Some examples illustrate the method; one of them is included in the XXVII case of the Painleve- Gambier classification. An explicit expression of its general solution in terms of two fundamental sets of solutions for two related second-order linear equations is also obtained. PB Oxford University Press SN 1464-3634 YR 2017 FD 2017 LK http://hdl.handle.net/10498/33829 UL http://hdl.handle.net/10498/33829 LA eng DS Repositorio Institucional de la Universidad de Cádiz RD 10-may-2026