Eigenvalue Problem of Nonlinear Semipositone Higher Order Fractional Differential Equations

We study the eigenvalue interval for the existence of positive solutions to a semipositone higher order fractional differential equation = = ??where ,??, , , satisfying , is the standard Riemann-Liouville derivative, , and is allowed to be changing-sign. By using reducing order method, the eigenvalue interval of existence for positive solutions is obtained