<math xmlns='http://www.w3.org/1998/Math/MathML'><semantics><mrow xref='id13'><mrow xref='id11'><mrow><mo>-</mo><mrow xref='id3'><mi xref='id1'>y</mi><mo>⁡</mo><mfenced><mi xref='id2'>x</mi></mfenced></mrow></mrow><mo>+</mo><mrow xref='id10'><mfrac><mo>ⅆ</mo><mrow><mo>ⅆ</mo><mi xref='id4'>x</mi></mrow></mfrac><mrow xref='id9'><mfrac><mo>ⅆ</mo><mrow><mo>ⅆ</mo><mi xref='id5'>x</mi></mrow></mfrac><mrow xref='id8'><mi xref='id6'>y</mi><mo>⁡</mo><mfenced><mi xref='id7'>x</mi></mfenced></mrow></mrow></mrow></mrow><mo>=</mo><mn xref='id12'>0</mn></mrow><annotation-xml encoding='MathML-Content'><apply id='id13'><eq/><apply id='id11'><plus/><apply><minus/><apply id='id3'><ci id='id1'>y</ci><ci id='id2'>x</ci></apply></apply><apply id='id10'><diff/><bvar><ci id='id4'>x</ci></bvar><apply id='id9'><diff/><bvar><ci id='id5'>x</ci></bvar><apply id='id8'><ci id='id6'>y</ci><ci id='id7'>x</ci></apply></apply></apply></apply><cn id='id12' type='integer'>0</cn></apply></annotation-xml><annotation encoding='Maple'>-y(x)+diff(diff(y(x),x),x) = 0</annotation></semantics></math>