x=0则lny=0y=1两边对x求导[1/(x²+y)]*(x²+y)'=3x²+cosx(2x+y')/(x²+y)=3x²+cosxy'=(x²+y)(3x²+cosx)-2x即dy/dx=(x²+y)(3x²+cosx)-2xx=0,y=1所以dy/dx(x=0)=1
