Question

若xy/(x+y)=3,则(6x+4xy+6y)/(9x+4xy+9y)=______

要过程

Answer 1

XY/（X+Y）=3，XY=3（X+Y）
原式=［6（X+Y）+4XY］/［9（X+Y）+4XY］
=［6（X+Y）+12（X+Y）］/［9（X+Y）+12（X+Y）］
=［18（X+Y）］/［21（X+Y）］
=18/21
=6/7

Answer 2

显然xy=3(x+y)
替换所有的xy
=(6x+4*3(x+y)+6y)/(9x+4*3(x+y)+9y)
=[18(x+y)]/[21(x+y)]
=18/21
=6/7

Answer 3

xy/(x+y)=3 则xy=3(x+y) 代入得
(6x+4xy+6y)/(9x+4xy+9y)
=[18(x+y)]/[21(x+y)]
=18/21
=6/7

Answer 4

xy/(x+y)=3可得xy＝3(x+y）
则原式(6x+4xy+6y)/(9x+4xy+9y)＝6xy/7xy＝6/7

Answer 5

6/7

追问

过程也要！！！不然我弄不懂的