已知1/x+1/y=5,求2x-3y+2y/-x+2xy-y_数学解答

已知1/x+1/y=5,求2x-3y+2y/-x+2xy-y

人气：212 ℃　时间：2020-01-28 18:15:16

解答

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