5x^2-7xy-6y^2=0

x+y=8,xy=-2,求(5xy+4x+7y)+(6x-3xy)-(4xy-3y)的值 5x^2-7xy-6y^2=0 已知x+y=2xy,且xy不等于0,则求-2x+6xy-2y/(7x+5y)-9xy-(3x+y)=___ 已知x>0,y>0,且x+6y=5根号xy,求(2x+根号xy-y)分之(x+根号xy+2y)的值 解二元二次方程组：6x^2-5xy+y^2=0 ,x^2+xy+y^2=7 解二元二次方程组：6x^2-5xy+y^2=0 ,x^2+xy+y^2=7 已知X-XY-2Y=0求2X+3XY-Y/X-2XY+5Y 若x+y-5xy=0,求(2x-3xy+2y)/(x+2xy+y)的值 诺x+y=6,xy=4 求(5x-4y-3xy)-(8x-y+2xy) 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>0,y>0,x+根号xy-6y=0,求4x+5根号xy-6y分之x+2根号xy 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=3xy,且xy不等于0,则-3x+6xy+3y/(7x-5y)-9xy-(3x-y) 1.xy-3x=40;x=52.7x-xy=-18;x=-63.3xy-28=16x;x=44.9y+6xy=30;x=-65.y-2xy=15;x=-16.4x+7y+5xy=0;x=1 6（x-y)-7(xy)=21,2(x-y)-5(x+y)=-1 5x^2+7xy+6y^2=0求x/y 2x^+xy-y^-4x+5y-6=? 已知：x^2 + xy - 6y^2=0,且xy不等于0求2x^2-3xy+y^2/5x^2-7xy+2y^2的值