2:3=4:x=6:y求xy

诺x+y=6,xy=4 求(5x-4y-3xy)-(8x-y+2xy) x^+2xy+y^+4=16 x^-2xy+y^=16 求(3xy+6y^)+|x^-(2xy+2y^-3x^)|的值 1-2/x+y=xy,4y+6x=xy.求xy的解? 当x-y=2xy时,求4x-3xy-4y/xy 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=4,xy=-2,求代数式3(xy+2y)-(xy-6x)的值 已知x+y=4,xy=-2,求代数式3（xy+2y）-（xy-6x） x+y=8,xy=-2,求(5xy+4x+7y)+(6x-3xy)-(4xy-3y)的值 若x+y=4,x-y=6,求xy(y^2+y)-y^2(xy+2x)-3xy的值. 已知；x+y=4,x-y的绝对值=6,求xy(y的平方+y)-y的平方（xy+2x）-3xy先化简再求值 已知x+y=4,xy=3,求4{xy+2y}+{6x-[2xy-y-3x}}的值 x+y=-4 若x+y=4 x-y=6 求xy(x^2+y)-y^2(xy+2x)-3xy的值求值 已知x+y=-2,求代数式(6xy+10y)+[4x-2(3xy+2y-x)] 已知x-y=6,xy=-1,求(2x+3x-2xy)-(x+4y+xy)-(3yx-2x+2y)的值 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x-y=4xy,求2x+3xy-2y/x-2xy-y的值 x-y=4xy,试求2x+3xy-2y/x-2xy-y