x²+y²=e^2y，x²=e^2y-y²对x求导2x=e^2y(2y')-2yy'，y'=x/(e^2y-y)，xy'=x²/(e^2y-y)对y求导2xx'=2e^2y-2y，x'=(e^2y-y)/x，x'y=(e^2y-y)y/x
