x=x(t)y=y(t)dx/dt=x'(t)dy/dt=y'(t)y'(x)=dy/dx=dy/dt /(dx/dt)=y'(t)/x'(t) y"(x)=d^2y/dx^2=d(y'(x))/dx=d(y'(x))/dt /(dx/dt)=d(y'(t)/x'(t))/dt /x'(t)=[y"(t)x'(t)-y'(t)x"(t)])/[x'(t)]^3
查高数去，有参数方程求导公式
游客1
x=x(t)
y=y(t)
dx/dt=x'(t)
dy/dt=y'(t)
y'(x)=dy/dx=dy/dt /(dx/dt)=y'(t)/x'(t)
y"(x)=d^2y/dx^2=d(y'(x))/dx=d(y'(x))/dt /(dx/dt)=d(y'(t)/x'(t))/dt /x'(t)=[y"(t)x'(t)-y'(t)x"(t)])/[x'(t)]^3
游客2
查高数去，有参数方程求导公式