3x^2y-[2xy^2-4(1/2xy-3/4x^2y)+xy]+3xy^2,其中x=3,y=-1/3

XY(XY+3)+(XY+4)+4(X+Y+1)-(X+Y+2) xy-2{xy-[3x^2y-(4xy^2+0.5xy)]+4x^2y}+6xy^2 （X-3xy+4xy-y）-[-2x-2（xy-3/2xy）-y]+6xy的过程 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 (-3xy+2xy)-(4xy+xy) 2x²y-3(2xy-xy)-xy 计算3xy[2xy-x(y-2)+x-1] （-3x^y+2xy)-( )=4x^+xy 化简：3x^2-[5xy-(x^y-3xy)+4x^2y-8xy] (x^2+2xy+y^2-4xy)*(x^2-2xy+y^2+4xy) 若x-y=4,xy=1,求(-2xy+2x+3y)-(3xy+2y-2x)-(x+4y+xy)的值 (-2xy+2x+5y)-(3xy+2y-2x)-(x+4y+xy)其中x-y=4xy=-1 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 化简 2（xy-xy²+3）-（-4xy²+xy-1） 其中,x等于--4,y等于-3 若x-y=4,xy=1,则(2x+y-2xy)-(3x+2y+xy)-(4xy+3y-5x)= x^3y(-4y)^2+(-7xy)^2*(-xy)-5xy^3*(-3x)^2 5x^3y*(-3y)^2+(-6xy)^2*(-xy)+xy^3*(-4x^2)