（1).(5x-3y+2xy)-(6x+4y-3xy) （2).3(5m-6n)+2(3m-4n)(3).2x的3次方-[2x-（3x的平方+4x-x的3次方）](4).5(a的平方b-2ab的平方+c)-4(2才+3a的平方b-ab的平方)(5).若(x+1)的平方+│y-2│=0,求3x的平方-[5xy-(x的平方y-3xy)+4x的

因式分解 x-xy+3y-3x 2x+xy-y-4x+5y-6 1、(-7x^y)(2x^y-3xy^3+xy) 2、((x-y)^6)/((y-x)^3)/(x-y) 4xy-[(x²+5xy-y²)-(3xy-1/2y)]x=3,y=-6 5x^3y*(-3y)^2+(-6xy)^2*(-xy)+xy^3*(-4x^2) 已知2/X-1/Y=3,则(X-2Y-XY)/(5XY+6Y-3X)=? 已知2/x-1/y=3,则(2y-x+4xy)/(3x-6y-5xy)=? 因式分解x(x+1)(x^2+5x+6)-8 x^ 2+5xy+x+3y+2y^2 诺x+y=6,xy=4 求(5x-4y-3xy)-(8x-y+2xy) 已知xy/x+y=1/2,则代数式3x-5xy+3y/-x+3xy-y= 计算：(5-xy/x^3-x^2y)/(1-5/xy)^2*(y-x)^3 x²-y²+5x+3y+4（x+y-2xy)(x+y-z)+(xy-1）² 先化简,再求值：-4x+7x-5-3x-6x+2,其中x=-2分之1 4xy-3x-xy先化简,再求值：-4x+7x-5-3x-6x+2,其中x=-2分之14xy-3x-xy+y+x-3xy-2y+2x+x,其中x=-5,y=-1 若x-y=4,xy=1,则(2x+y-2xy)-(3x+2y+xy)-(4xy+3y-5x)= (-2xy+2x+5y)-(3xy+2y-2x)-(x+4y+xy)其中x-y=4xy=-1 5x^2y/-1/2xy*3xy^2 5xy^2-{2x^y-[3xy^2-（xy^2-2x^2y）]/（-1/2xy）} (x-2xy)*(-xy+2y*y)-(3x*x-2xy)(x-9xy+6y*y)答案应为-2x-x*x-3x， 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