研究一类含拟二次项和拟三次项的多项式系统极限环分支问题,首先利用数学软件Mathematica计算出该系统在原点前18个奇点量的表达式,从而导出原点成为中心及最高阶细焦点的条件,并在此基础上给出了该系统在原点附近分支出5个极限环的实例.
In this paper, we study bifurcation of limit cycles for a class of polynomial system with quasi quadratic terms and quasi cubic terms . Firstly, the eighteen singular point quantities at the origin are computed by using of Mathematica. The conditions of the origin to be the center and to bethe highest degree fine focus are derived. Basing on them, this system which allows the appearance of five limit cycles in the neighborhood of origin is constructed.