x^2-5xy+6y^2-3x+4y-10因式分解,十字相乘法

因式分解 x-xy+3y-3x 2x+xy-y-4x+5y-6 4xy-[(x²+5xy-y²)-(3xy-1/2y)]x=3,y=-6 x²-y²+5x+3y+4（x+y-2xy)(x+y-z)+(xy-1）² 5x^3y*(-3y)^2+(-6xy)^2*(-xy)+xy^3*(-4x^2) 已知2/x-1/y=3,则(2y-x+4xy)/(3x-6y-5xy)=? 1、(-7x^y)(2x^y-3xy^3+xy) 2、((x-y)^6)/((y-x)^3)/(x-y) 诺x+y=6,xy=4 求(5x-4y-3xy)-(8x-y+2xy) (-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)= 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 因式分解 （3x+2y）-（x-y）² x²-xy+3y-3x 2x²+xy-y²-4x+5y-6 化简：3x^2-[5xy-(x^y-3xy)+4x^2y-8xy] 因式分解 求过程 x-xy+3y-3x 2x+xy-y-4x+5y-6 3x平方-5x平方y-{2x平方y+6xy平方-[2xy平方-3x平方y+(3x平方y-4xy平方】} 计算：（1）8x^2y^2*(-3x/4y^5) (2)(x+y)^2/xy-y^2*(y-x)^2/xy+y^2 因式分解:12xy^2(y-x)+xy^3(x-y)+4x^2y(x-y) 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 1.已知x+y=-4,xy=3,求5（2分之1xy+2y）+[6x-(2xy+y-3x)]的值2.已知（x+3）^2+|x-y+10|=0求代数式5x^2y-[2x^2y-(3xy-xy^2)-3x^2]-2xy^2-y^2的值