F(x)=f(x)·g'(x)-f'(x)·g(x) F'(x)=f(x)·g''(x)-f''(x)g(x)F(x)=f(x)·g(x) F'(x)=f(x)·g'(x)-f'(x)·g(x) F''(x)=f(x)·g''(x)+2f'(x)·g'(x)+f''(x)g(x)