Abstract: Based on classical harmonic balance method, a technique
is used to solve a quadratic nonlinear oscillator. This technique was previously
used to determine higher approximate periodic solutions of some nonlinear
oscillator equations in which the nonlinear function satisfies With this procedure,
excellent approximate period and the correspondingperiodicsolutionareobtained. The method is
illustrated by an example.
Keywords and phrases: harmonic balance, quadratic nonlinear oscillator.
