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已知x-y=3xy,则2x+3xy-2y除以x-2xy-y=? 要过程.

法一 上下同时除以xy, 得(1/y-2+1/x)/(2/y+3+2/x)=(1/x+1/y-2)/(2(1/x+1/y)+3)=(3-2)/(2*3+3)=1/9 法二 1/x+1/y=3 (x+y)/xy=3 x+y=3xy (x-2xy+y)/(2x+3xy+2y)=xy/9xy=1/9 法三 同法二 得x+y=3xy xy=(x+y)/3 (x-2xy+y)/(2x+3xy+2y)=[(x...

y=3xy+x x-y=-3xy 所以: x-2xy-y分之2x+3xy-2y =2(x-y)+3xy/(-3xy-2xy)/ =-6xy+3xy/5xy =-3xy/-5xy =3/5

(x-2xy-y)分之(2x+3xy-2y) =(x-y-2xy)分之(2x-2y+3xy) =(4xy-2xy)分之(8xy+3xy) =2xy分之11xy =2分之11

分子分母同时除以xy, 原式=(2/y+3-2/x)/(1/y-2-1/x) =[3-2(1/x-1/y)]/[-2-(1/x-1/y)] =[3-2*3]/[-2-3] =-3/(-5) =3/5

因为1/x—1/y=3,所以x—y=—3xy。分式(x—2xy—y)/(2x+3xy—2y)=(—5xy)/(—3xy)=5/3

1/x-1/y=-3 (y-x)/xy=-3 y-x=-3xy (2x+3xy-2y)/(x-2xy-y) 9xy/xy=9

已知x等于3xy加y,求代数式(x-2xy-y)分之(2x+3xy-2y)的值 x=3xy+y x-y=3xy 所以 (2x+3xy-2y)/(x-2xy-y) =[2(x-y)-3xy]/[(x-y)-2xy] =(6xy-3xy)/(3xy-2xy) =(3xy)/(xy) =3

已知1/x+1/y=5 得(x+y)/(xy)=5则x+y=5xy (2x-3xy+2y)/(x+2xy+y) =(2*5xy-3xy)/(5xy+2xy) =7xy/(7xy) =1

1/x+1/y=5 (2x-3xy+2y)/(x+2xy+y) 分子分母同除以xy得: = (2/x-3+2/y) / (1/x+2+1/y) = {2(1/x+1/y)-3} / {(1/x+1/y)+2} = {2*5-3} / {5+2} = 7/7 = 1

已知等式两边同乘以 xy ,得 y-x = 3xy, 然后代入所求式子,可得原式= (7xy-6xy) / (-3xy-2xy) = -1/5 。

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