（3x+xy+3y）/(x-xy+y)=[3( x+y)+xy]/(x+y-xy)
=4xy/(2xy)
=2
2.已知1\/x+1\/y=3,则(3x+xy+3y)\/(x-xy+y)=( ).
因为 1\/x+1\/y=3,所以 x + y = 3xy,代入:（3x+xy+3y）\/(x-xy+y)=[3( x+y)+xy]\/(x+y-xy)=4xy\/(2xy)=2
已知1\/x+1\/y=3 求3x+xy+3y\/x-xy=y的值
解：(3x+xy+3y)\/(x-xy+y) 上下同除以xy =(3\/y+1+3\/x） \/ (1\/y-1+1\/x)=[3(1\/x+1\/y)+1] \/ (1\/x+1\/y -1)=(3×3+1)\/(3-1)=10\/2 =5
已知1\/x-1\/y=3,求分式3x-xy+3y\/x+xy+y的值.
已知1\/x-1\/y=3,应该是1\/x+1\/y=3,[按原式得不出结果!]如此,则3xy＝x+y （3x-xy+3y）\/（x+xy+y）＝2
已知1\/x+1\/y=3,求(3x-5xy+3y)\/(x-2xy+y)
1\/x+1\/y=3 去分母得 x+y=3xy (3x-5xy+3y)\/(x-2xy+y)=[3(x+y)-5xy]\/(x+y-2xy)=(9xy-5xy)\/(3xy-2xy)=4xy\/xy=4
已知,1\/x+1\/y=3,求3x-2xy+3y\/x+5xy+y的值
把分子、分母同除以xy，再把已知代入可得 原式=（3-2）\/(3+5)=1\/8
已知x分之1+y分之1=3,求x+xy+y分之3x-2xy+3y的值
数理答疑团为您解答，希望对你有所帮助。1\/x +1\/y =3,(x+y)\/xy=3,x+y=3xy,(3x-2xy+3y)\/(x+xy+y)=(7xy)\/(4xy)=7\/4 祝你学习进步，更上一层楼！(*^__^*)
若1\/x+1\/y=3,则x\/3x+3y+y+2xy\/3x+3y=
1\/X+1\/Y=3,X+Y=3XY,∴X\/(3X+3Y)+(Y+2XY)\/(3X+3Y)=(X+Y+2XY)\/3(X+Y)=(3XY+2XY)\/9XY =5\/9.
已知1\/x-1\/y=3,求(3x+4xy-3y)\/(x-2xy-y)的值
1\/x-1\/y通分=(y-x)\/xy=3 y-x=3xy x-y=-3xy 所以原式=[3(x-y)+4xy]\/[(x-y)-2xy]=[3(-3xy)+4xy]\/[(-3xy)-2xy]=-5xy\/(-5xy)=1
一道初中数学题(要过程)
1\\x+1\\y=3同乘xy得Y+X=3XY 原式=[3(X+Y)-4XY]\/[(X+Y)+2XY]=5XY\/5XY=1
已知1\\x+1\\y=3,求值 1)x+y+3xy+3y^2\\(2xy+y^2) 2)1\\(1-3x)*[1\\(1...
1\/x+1\/y=3通分 (x+y)\/xy=3 x+y=3xy (x+y+3xy+3y^2)\/(2xy+y^2)=(3xy+3xy+3y^2)\/(2xy+y^2)=(6xy+3y^2)\/(2xy+y^2)=3(2xy+y^2)\/(2xy+y^2)=3 1\/(1-3x)*[1\/(1-3y)]=1\/(1-3x)(1-3y)=1\/(1-3x-3y+9xy)=1\/[1-3(x+y)+9xy]=1\/[1-3*3xy+...
