1）4x^2+4xy-3y^2+4x+10y-32）x^4+y^4+z^4-2x^2y^2-2x^2z^2-2y^2z^2

x²-y²+5x+3y+4（x+y-2xy)(x+y-z)+(xy-1）² XY(XY+3)+(XY+4)+4(X+Y+1)-(X+Y+2) (x+y)(x+y+2xy)+(xy+1)(xy-1)(x+y)(x-y)+4(y-1) （1）3xy×(-4xy+2xy-1)（2）(x+2y)(3x-2y)+(x-2y)(3x+2y)因式分解 约分：（1）-4x^2y^3/10xy^4(2)（x^2-4xy+4y^2)(y-x)/(2y-x)(x^2-y^2) (1)ac分之2bc (2)xy²分之（x+y）y (3)(x+y)^2/x^2+xy (4)(x-y)^2/x^2-y^2 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 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 计算 2xy[4x²y²-3y（xy+x²y）-xy²]（2x-x²-3）（x³-x²-2）（x²）³-2x³[x³-x²（4x+1）]（-1/3xy）²·[xy（2x-y）-3x（xy-y²）] 整式乘法..1.3xy（x²y-xy²+xy）-xy²（2x²-xy+2x）2.（x-1）（x²-4x+3）-x（x²-5x+2) 计算：（1）8x^2y^2*(-3x/4y^5) (2)(x+y)^2/xy-y^2*(y-x)^2/xy+y^2 x²/xy-x/y 3x/4x+y - x-2y/4x+y (1-y/y+x)÷x/y²-x² (x²-4y²)÷(2x+y)/xy×1/x(2y-x）(2x+y)/xy 1/x(2y-x） 都是一项 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 化简求值x-4y/2x-7xy+3y×x-2xy-3y/2x+3xy-2y÷3x-6y/4x-4xy+y,其中：x=1999,y=-1