\[
\boxed{
{\frac {\rm d}{{\rm d}x}}y \left( x \right) -{\it R1} \left( x,\sqrt {{\it a4}\,{x}^{4}+{\it a3}\,{x}^{3}+{\it a2}\,{x}^{2}+{\it a1}\,x+{\it a0}} \right) {\it R2} \left( y \left( x \right) ,\sqrt {{\it b4}\, \left( y \left( x \right)  \right) ^{4}+{\it b3}\, \left( y \left( x \right)  \right) ^{3}+{\it b2}\, \left( y \left( x \right)  \right) ^{2}+{\it b1}\,y \left( x \right) +{\it b0}} \right) =0}
\]