运用变分方法探讨了一类三阶微分方程 x碶(t)+ f (x′(t))+ h(x(t))x′(t)+β(t)g(x(t-τ(t)))= p(t)的2π‐周期解的存在性,获得周期解存在的一个充分条件,同时推出一个相关推论。%The existence of 2π‐periodic solutions for the third order differential equation x‴(t)+ f (x′(t))+ h(x(t))x′(t)+β(t)g(x(t-τ(t)))= p(t) is explored by the variational methed ,a sufficient condition for the periodic solutions is obtained , and a relevant corollary is also provided .
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