已知6x^2-7xy-3y^2+14x+y+a=(2x-3y+b)(3x+y+c),则……已知6x^2-7xy-3y^2+14x+y+a=(2x-3y+b)(3x+y+c),则a=?,b=?,c=?

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 已知X+y=6,xy=7 求x^2y+xy^2=已知X+y=6,xy=7 x^2y+xy^2 已知:x/y=-2,求x^2-2xy-3y^2/x^-6xy 已知xy/x+y=3,则代数式2x-7xy+2y/-x+xy-y的值是多少? 已知xy/x+y=6,求3x-2xy+3y/-x+3xy-y的值. 已知(xy)/(x+y)=6求(3x-2xy+3y)/(-x+3xy-y)的值. 已知xy^2=-6,求-xy(x^3y^7-3x^2y^5-y）的值 已知x的相反数为y-6,y的倒数为2x,求出代数式(5xy+4x+7y)+3(2x-xy)-(4xy-3y)的值 已知x的相反数为y-6,y的倒数为2x,求出代数式(5xy+4x+7y)+3(2x-xy)-(4xy-3y)的值 已知x/y=2,求 [x^2-xy+3xy^2 ] / [ x^2+xy+6y^2]的值 1、(-7x^y)(2x^y-3xy^3+xy) 2、((x-y)^6)/((y-x)^3)/(x-y) 已知xy^2=-2求xy（2x^3y^7+5x^2y 已知x+y=6,xy=-3,则x^2y+xy^2=? 已知x+y=6,xy=-3,则x∧y+xy∧2= 已知x=3y,试求（x-y)^2+2xy-y^2/x^2+7xy+y^2 已知x=3y,试求(x-y)^2+2xy-y^2/x^2+7xy+y^2 已知x/2=y/3（xy≠0）,求x²-2xy-3y²/x²-6xy-7y²的值 已知1/x - 1/y = 2,求3x+7xy-3y / 2x-3xy-2y的值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)=-1/71/x-1/y=2到(y-x)/xy=2 是怎么变化的.. 已知xy=-2,x-y=3,求（x+y)（x-y)-y^2+（x-y)^2-（6x^2y-2xy^2)÷2y