[㏑f(x)]'=[v(x)·㏑u(x)]'f'(x)/f(x)=v'(x)·㏑u(x)+v(x)u'(x)/u(x)y'/y=v'(x)·㏑u(x)+v(x)u'(x)/u(x)y'=y[v'(x)·㏑u(x)+v(x)u'(x)/u(x)]=u(x)^v(x)[v'(x)·㏑u(x)+v(x)·u'(x)/u(x)]
