已知1/Y-1/X=3,求3X-2XY-3Y/X+XY-Y的值

已知1/Y-1/X=3,求3X-2XY-3Y/X+XY-Y的值
已知1/Y-1/X=3,求3X-2XY-3Y/X+XY-Y的值

已知1/Y-1/X=3,求3X-2XY-3Y/X+XY-Y的值
xy(1/Y-1/X)
=x-y
=3xy
3X-2XY-3Y/X+XY-Y
=3(x-y)-2xy/(x-y)+xy
=9xy-2xy/3xy+xy
=7xy/4xy
两边同时约去xy
原式=7/4

0

这样吧