y-e^(-xy)=x-e^(xy)
dy/dx-e^(-xy)*(-y-x*dy/dx)=1-e^(xy) *(y+x*dy/dx)
dy/dx+e^(-xy)*(y+x*dy/dx)=1-e^(xy) *(y+x*dy/dx)
(1+xe^(-xy)+xe^(xy))*dy/dx=1-ye^(xy)-ye^(-xy)
dy/dx=[1-ye^(xy)-ye^(-xy)]/(1+xe^(-xy)+xe^(xy)).
y-e^(-xy)=x-e^(xy)
dy/dx-e^(-xy)*(-y-x*dy/dx)=1-e^(xy) *(y+x*dy/dx)
dy/dx+e^(-xy)*(y+x*dy/dx)=1-e^(xy) *(y+x*dy/dx)
(1+xe^(-xy)+xe^(xy))*dy/dx=1-ye^(xy)-ye^(-xy)
dy/dx=[1-ye^(xy)-ye^(-xy)]/(1+xe^(-xy)+xe^(xy)).