三阶导数如下:y=e^f(x)y'=e^f(x)×f'(x)y"=e^f(x)×f'(x)^2+e^f(x)×f"(x)=e^f(x)[f'(x)^2+f"(x)]y"'=e^f(x)f'(x)[f'(x)^2+f"(x)]+e^f(x)[2f'(x)f"(x)+f"'(x)]y"'=e^f(x)[f'(x)^3+3f'(x)f"(x)+f"'(x)]
