2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/80700In this letter we show that the force-free Duffing-van der Pol oscillator is completely integrable for a specific parametric choice. We derive a general solution for this parametric choice. Further, we describe a procedure to construct the transformation which removes the time dependent part from the first integral and provide the general solution by quadrature. The procedure is shown to have a wider applicability through additional examples. We also show that through our method one can deduce linearizing transformations in a simple and straightforward way and illustrate it with a specific example.8 pages, 1 figure, J. Phys. A: Math. Gen. 37 (2004) to appearExactly Solvable and Integrable SystemsMathematical Physicstext