Hi, This is equation I need to find solutions for d2u/d2x + 1/2Lu = 0 where L(x) I understand we can remove fraction from second term. 2 [d2 u/d2x ] + Lu = 0 now how do I find solution of this equation ? How do we deal with L ? because usually we have Y'(dy/dx or in this case du/dx ) or Y (in this case u) in second term in an ode. Thanks.