x^3+y^3+x^2=xy两边对X求导3x^2+3y^2*y'+2x=y+xy'3y^2*y'-xy'=y-3x^2-2x(3y^2-x)y'=y-3x^2-2xy'=(y-3x^2-2x)/(3y^2-x)把点(1,-1)代入得k=(-1-3-2)/(3-1)=-3所以点（1-1）处的切线方程是y+1=-3(x-1)=-3x+3y=-3x+2...