(uv)'=lim(h→0)[u(x+h)v(x+h)-uv]/h
=lim(h→0)[u(x+h)v(x+h)+u(x+h)v-u(x+h)v-uv]/h
=lim(h→0)[u(x+h)]×[v(x+h)-v(x)]/h+lim(h→0)[v(x)]×[u(x+h)-u(x)]/h
=u(x)v'(x)+u'(x)v(x)
=u'v+uv'
(u/v)'=[u*v^(-1)]'
=u'*[v^(-1)]+[v^(-1)]'*u
=u'*[v^(-1)]+(-1)v^(-2)*v'*u
=u'/v - u*v'/v²
通分得
(u/v)=(u'v-uv')/v²
累死我了,请加分!