若x-y=5,-xy=3,求(7x+4x+xy)-6(5/6y+x-xy)

问题描述:

若x-y=5,-xy=3,求(7x+4x+xy)-6(5/6y+x-xy)

(7x+4y+xy)-6(5/6y+x-xy)
=7x+4y+xy-5y-6x+6xy
=x-y+7xy
=5+7×(-3)
=-16如图,点c是线段AB的三等分点,点D在CB伤,CD:DB=17:2 ,且CD-AC=3cm,求AB的长