| In this paper, we consider a class of second-order two-point boundary value problem~~ $x^{\prime\prime}(t)+f(t,x(t),x^{\prime}(t))=0,~~ t\in (0, 1)$, $a x(0)-b x^\prime(0)=0, ~~c x(1)+d x^\prime(1)=0$,~~ where $f:[0,1]\times R^2\longrightarrow R$ is continuous, $ a>0,b\ge 0,c>0$, and $d\ge 0$. By using upper and lower solutions method and Schauder degree theory, we obtain the existence of three solutions. |
