一、1/4（x^+y^)-1/2xy （^等于平方）二、75x^-27x* (^等于平方,*等于六次方）三、x^-4y^+x+2y （^等于平方）

(x+y)(x+y+2xy)+(xy+1)(xy-1)(x+y)(x-y)+4(y-1) 4x²y一[6xy一2(4xy-2)-x²y]十1,其中x=一½,y=1. 一道高一因式分解练习题(x+y-2xy)(x+y-2)+(xy-1)^2 XY(XY+3)+(XY+4)+4(X+Y+1)-(X+Y+2) 1-2/x+y=xy,4y+6x=xy.求xy的解? 己知x平方+3xy一4y平方=0(y≠0)求代数式(1)y分之x(2)x+y分之x一y 求解一初中二元一次方程（x+4)(y-1)=xy(x-2)(y+1)=xy求XY的值.5分钟内给十分! 已知1/x十1/y=3,求3x一4xy十3y/x十2xy十y的值 .(x+y-2)(x+y-2xy)+(xy-1)^2 已知1/x-1/y=2,求3x+7xy-3y/2x-3xy-2y答案是1/x-1/y=2(y-x)/xy=2 得：x-y=-2xy(3x+7xy-3y)/(2x-3xy-2y)=[3(x-y)+7xy]/[2(x-y)-3xy]=(-6xy+7xy)/(-4xy-3xy)=xy/(-7xy)=-1/7 谁能帮我解释一下=[3(x-y)+7xy]/[2(x-y)-3xy]=(-6xy+7xy)/(-4xy-3xy) 是怎 x-2xy-1+4y² (-2xy+2x+5y)-(3xy+2y-2x)-(x+4y+xy)其中x-y=4xy=-1 若x-y=4,xy=1,求(-2xy+2x+3y)-(3xy+2y-2x)-(x+4y+xy)的值 若x-y=4,xy=1,则(2x+y-2xy)-(3x+2y+xy)-(4xy+3y-5x)= x-y=1,xy=2.求：(-2xy+2x+3y)-(3xy+2y-2x)-(x+4y+xy)的值 .已知:x-y=1,xy=-2.求:(-2xy+2 x+3y)-(3xy+2y-2x)-(x+4y+xy)的值 x-y/x^2+xy除以xy-x^2/x^2y^2-x^4*1/x-y 化简:[4xy(x-y)^-1 + (xy^-1 - x^-1y)/(x^-1 + y^-1)] / (x+y)^2