2x^2+4xy+2y^2+7x+7y+3因式分解

x^3y(-4y)^2+(-7xy)^2*(-xy)-5xy^3*(-3x)^2 1、(-7x^y)(2x^y-3xy^3+xy) 2、((x-y)^6)/((y-x)^3)/(x-y) 因式分解:8(x-2y)-x(7x+y)+xy. 计算(x^8-x^7y+x^5y^3-x^4y^4+x^3y^5-x^y^7+y^8)(x^2+xy+y^2) 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 求（3x^+y^-5xy）-【2x^-（-4xy-y^+7x^）】=? 求（3x^+y^-5xy）-【2x^-（-4xy-y^+7x^）】=? 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 因式分解：x^2-xy-2y^2+x+7y x^2-xy-2y^2+x+7y-6 (x+y)(x+y+2xy)+(xy+1)(xy-1)(x+y)(x-y)+4(y-1) x²+xy-2y²-x+7y-6 计算:2xy/(x+y)².(x+y)/4y 3(x-y)²-7(x-y)+8(x-y)²+6(x-y)求详细过程（2） 5xy-4x²y-8xy²+3xy-xy²+4x²y (4x^2+5xy-7x)-(5x^2y+4xy+x) 2*X平方-4Y平方=7XY,XY不等于零,求Y/X 已知x-y=8 xy=7,则3xy-2x+2y+4(y-x)²=?