\[
\boxed{
{\frac {{\rm d}^{2}}{{\rm d}{x}^{2}}}y \left( x \right) +{\frac {{k}^{2}{\it JacobiSN} \left( x,k \right) {\it JacobiCN} \left( x,k \right) {\frac {\rm d}{{\rm d}x}}y \left( x \right) }{{\it JacobiDN} \left( x,k \right) }}+{n}^{2}y \left( x \right)  \left( {\it JacobiDN} \left( x,k \right)  \right) ^{2}=0}
\]