y-xe^y=1当x=0时,y=1两边同时对x求导得dy/dx-e^y-xe^y*dy/dx=0dy/dx=e^y/(1-xe^y)dy/dx|(x=0,y=1)=ed^2y/dx^2=e^y*dy/dx*(1-xe^y)-e^y*(-e^y-xe^y*dy/dx)/(1-xe^y)^2 |(x=0,y=1)=[e*e-e*(-e)]/1=2e^2
