西要毛子律技大学XIDIANUNIVERSITY.. f(a)ld(a)同理可得g(a) / d(a)::f(a)g(a) /d,(a)d,(a),即d(a)ld(a)d(a)故 d(a)=d,(2)d,(a)同理可得 2 g d ( ) | ( ).   1 2  f g d d ( ) ( ) | ( ) ( ),     即 1 2 d d d ( ) | ( ) ( )    1  f d ( ) | ( ).   故 1 2 d d d ( )= ( ) ( )   