般地 f(x)=u(x)"(x(u(x)>0 lnf(x)=v(x)·Inu(x) 又∴Inf(x) ∫(x) d x f(r dc f(x)=f(x)·,I∫(x) f(r=u(x)v(x).Inu(x)+ (x)u'(x) u(r)一般地 ( ) ( ) ( ( ) 0) ( ) f x  u x u x  v x  ln f (x)  v(x) lnu(x) ( ) ( ) 1 ln ( ) f x dx d f x f x dx d 又   ( ) ( ) ln f (x) dx d  f  x  f x  ] ( ) ( ) ( ) ( ) ( ) [ ( ) ln ( ) ( ) u x v x u x f x u x v x u x v x       