Have you tried it? If [itex]sin(y) + xy  x^3=2[/itex] then [itex]cos(y)y'+ y+ xy' 3x^2= 0[/itex]. Differentiating again, [itex]sin(y)(y')^2+ cos(y)y''+ 2y'+ xy'' 6x= 0[/itex].
You can you those to see if the differential equation is satisfied or not.
