Abstract
In this investigation, an (un)forced third-order/jerk Van-der Pol oscillatory equation is solved using two perturbative methods called the Krylov-Bogoliubov-Mitropolsky method and the multiple scales method. Both the first- and second-order approximations for the unforced and forced jerk Van-der Pol oscillatory equations are derived in detail using the proposed methods. Comparative analysis is performed between the analytical approximations using the proposed methods and the numerical approximations using the fourth-order Runge-Kutta scheme. Additionally, the global maximum error to the analytical approximations compared to the Runge-Kutta numerical approximation is estimated.