By using some differential inequality, a second-order delay differential equation(r(t)x′(t))′ + p(t)x(q(t)) = 0has been investigated and some necessary condition for this equation has a nonoscillatorysolution and some sufficient condition which ensures that all of the solutions of the aboveequation are oscillatory are obtained.
By using the Krasnoselskii's fixed point theorem for cones,conditions for the existence of positive solutions to the three-point boundary value problem for second order differential equation with an advanced argumentu″(t)+λa(t)f(u(h(t)))=0, t∈(0,1), u(0)=0, αu(η)=u(1),where 0<η<1,0<α<1η and t≤h(t)≤1 are obtained.
Zhu Lifei Li YongkunDept. of Math., Yunnan Univ., Yunnan 650091,China.
