令z=(-7x-6y)/(-7x-7y)=(-7x-7y+y)/(-7x-7y)=1-y/7(x+y)=1-2/7x
所以原题=1/z=7x/(7x-2)
不知道啊对
若xy\/x+y=2,则3x-5xy+3y\/-x+3xy-y=?
xy = 2(x + y)(3x - 5xy + 3y)\/(-x + 3xy - y)= [3(x + y) - 10(x + y)]\/[-(x + y) + 6(x + y)]= -7(x + y)\/5(x + y)= -7\/6
如果xy\/x+y=2,那么3x-5xy+3y\/-x+3xy-y=?
xy=2(x+y)3x-5xy+3y\/-x+3xy-y =(3(x+y)-10(x+y))\/(6(x+y)-(x+y))=-7\/5
如果XY\/X+Y=2,求代数式3X-5Y+3Y\/-X+3XY-Y的值为 ?没错!
分子的"-5Y"和"+3Y"是同类项 若是"代数式3X-5XY+3Y\/-X+3XY-Y的值为 "则答案是 3X-5XY+3Y\/-X+3XY-Y =（3X-5XY+3Y）\/（-X+3XY-Y）=[3(X+Y)\/(XY)-5]\/[3-（X+Y)\/(XY）]=(3\/2-5)\/(3-1\/2)=-7\/5 =-1.4 ...
已知xy\/x+y=2,求代数式3x-5y+3y\/-x+3xy-y的值
因为xy\/（x+y）=2 →(x+y)=xy\/2 则（3x-5y+3y）\/（-x+3xy-y）=[3(x+y)-5y]\/[-(x+y)+3xy]=[3*(xy\/2)-5y]\/[-xy\/2 +3xy]=(3xy\/2 -5y)\/(5xy\/2)=3\/5-2\/x
已知xy除以x+y=2,求代数式3x-5xy+3y除以﹣x+3xy-y的值
xy\/（x+y）=2 , xy=2（x+y）(x-5xy+3y)\/(﹣x+3xy-y)=(x-5*2（x+y）+3y)\/(﹣x+3*2（x+y）-y)=(3x-10x-10y+3y)\/(-x-6x-6y-y)=(-7x-7y)\/(-7x-7y)=1
已知xy\/x+y=2,求3x-5x+3y\/-x+3xy-y的值。
-5xy]\/[-(x+y)+3xy]=(3\/2xy-5xy)\/(-1\/2xy+3xy)=(3\/2-5)\/(3-1\/2)=-7\/5 你是不是分子分母写倒了 呵呵 若是xy 是分母 x+y是分子 (x+y)\/xy=2 x+y=2xy (-x+3xy-y)\/(3x-5xy+3y)=[-(x+y)+3xy]\/[3(x+y)-5xy]=(-2xy+3xy)\/(6xy-5xy)=xy\/(xy)=1 ...
已知xy分之x加y等于2,求3x减5xy加3y分之负x加3xy减y.急快...
xy分之x加y等于2 ∴x+y=2xy 3x减5xy加3y分之负x加3xy减y =[-(x+y)+3xy]\/[3(x+y)-5xy]=(-2xy+3xy)\/(6xy-5xy)=xy\/(xy)=1
以知XY除以X+Y等于2 求代数式3X--5XY+3Y除以(--X+3XY--Y) 提示把XY...
（3X--5XY+3Y）\/(--X+3XY--Y)=【3（X+Y）-5XY】\/【3XY-（X+Y）]上下同时除以（X+Y)得出：【3-5XY\/（X+Y)】\/3XY\/（X+Y)-1 =（3-10）\/（6-1）=-7\/5 XY\/（X+Y)=2
xy÷x+y=2求代数式三x+ay-5 xy÷-x-3 xy减y的值
比较简单,利用已知：XY÷（x+y)=2,可得出XY=2(X+Y),对需计算式,简单化简.将式中XY换成 2(X+Y),即可.但是需要注意分母中的符号.
已知x加y分之xy等于2,求负x加3xy减y分之3x减5xy加3y
\/(-x+3xy-y)xy\/(x+y) = 2得：xy=2(x+y)(3x-5xy+3y)\/(-x+3xy-y)=(3x-9xy+3y+4xy)\/(-x+3xy-y)= -3 + 4xy\/(-x+3xy-y)= -3 + 8(x+y)\/(-x+6x+6y-y)= -3 + 8(x+y)\/5(x+y)= -3 + 8\/5 = -7\/5 祝你学习进步，更上一层楼！ (*^__^*)...
