d/dx是对x求导dy/dx是y对x的导数,即yd^2y/dx^2即d/dx(dy/dx),是y对x的导数,即y,是二阶导数扩展资料例:y=x^2dy/dx=(x^2)'=2xd(x^2)/dx=2xd^2y/dx^2=(2x)'=2