二阶微分方程极限圆型分类问题的进一步探讨

FURTHER STUDY ON THE LIMIT CIRCLE CASE OF A CLASS OF LINEAR DIFFERENTIAL EQUATIONS OF SECOND ORDER

进一步研究二阶微分方程（ｒ（ｔ）ｘ′）′＋Ｐ（ｔ）ｘ′＋（ｑ＿１（ｔ）＋ｑ＿２（ｔ））ｘ＝０极限圆型的分类问题。借助于辅助函数，得到了该方程是极限圆型的若干判别准则。

The limit circle case of linear differential equation(r(t)x′)′+p(t)x′+(q_1(t)+q_2(t))x=0.with the aid of auxiliary functions is further studied. some sufficient conditions under whichthe above equation belongs to the L.S.or L.S.∩L.C.are obtained.