Positive Solutions of a Weak Semipositone Third-Order Three-Point Boundary Value Problem

Abstract:

      The positive solutions are studied for the nonlinear third-order three-point boundary value problem $$\begin{array}{c}u'''(t)=f(t,u(t)),~\mbox{a.e.}~t\in [0,1],\quad u(0)=u'(\eta)=u''(1)=0,\end{array}$$where the nonlinear term $f(t,u)$ is a Carath\'eodory function and there exists a nonnegative function $h\in L^{1}[0,1]$ such that$f(t,u)\geq -h(t)$. The existence of $n$ positive solutions is proved by considering the integrations of ``height functions'' and applying the Krasnosel'skii fixed point theorem on cone.