Question

证明(f(x)*g(x))'=f'(x)*g(x)+g'(x)*f(x)

Answer 1

lim(((u+du)(v+dv)-uv)/dx)=lim((udv+vdu+dvdu)/dx)=u'v+v'u

如果是要乘法公式对数方法简单一些

y=uv

lny=lnu+lnv

y'/y=u'/u+v'/v

y'=u'v+uv