已知1/x+1/y=5,求2x-3y+2y/-x+2xy-y

已知1/x+1/y=5,求2x-3y+2y/-x+2xy-y
已知1/x+1/y=5,求2x-3y+2y/-x+2xy-y

已知1/x+1/y=5,求2x-3y+2y/-x+2xy-y
1/x+1/y=(x+y)/xy=5
x+y=5xy
2x-3xy+2y/-x+2xy-y
=[2(x+y)-3xy]/[2xy-(x+y)]
=(10xy-3xy)/(2x-5xy)
=7xy/(-3xy)
=-7/3

1/x+1/y=5 (x+y)/xy=5 x+y=5xy x=5xy-y x=y(5x-1) y=x/(5x-1) 把y带进式子算