The Problem Is Not a Regular Sturm-Liouville Problem Under Which of the \left[

Multiple Choice

The problem $\frac { d } { d x } \left[ r ( x ) y ^ { \prime } \right] + ( q ( x ) + \lambda p ( x ) ) y = 0 , A _ { 1 } y ( a ) + B _ { 1 } y ^ { \prime } ( a ) = 0 , A _ { 2 } y ( b ) + B _ { 2 } y ^ { \prime } ( b ) = 0$ is not a regular Sturm-Liouville problem under which of the following conditions. Select all that apply.

A) $r = 1 / ( x - a )$ on $( a , b )$
B) $q ( x ) = 0$ on $[ a , b ]$
C) $p ( x ) = x - a$ on $[ a , b ]$
D) $A _ { 1 } A _ { 2 } = 0$
E) $A _ { 1 } ^ { 2 } + B _ { 1 } ^ { 2 } = 0$