f(x)=u(x)v(x)f'(x)=u'(x)v(x)+u(x)v'(x)f''(x)=u''(x)v(x)+2u'(x)v'(x)+u(x)v''(x)将函数分解后分别求好一次二次导数再代入化简吧，写起来确实繁琐
