1.2.3.已知|3x-2y-3|+(7x+3y-53)^2=0,求x与y的值.4.某地决定对一段常为180m的河道进行整治,由A B两个工程队先后接力完成.A工程队每天整治12m,B工程队每天整治8m,共用时20天.求A B两工程队分别整治河道

已知：2x+y=6,x-3y=1 求7y(x-3y)(x-3y)-2(3y-x)(3y-x) 已知2x-y=-3,求代数式5(x-3y)-2(x-7y) 已知x-y=3,求代数式7-x+y-(x-y)^2的值.-.- 已知X和Y满足3X+4Y=2,X-Y-1/7 已知x+2y=3则x=? x-y=7则y=? 已知（x+y）2 =2,(x-y)3 =3,求(x+y)7(x-y)2(x+y)3(y-x)4 的值 已知方程组{(X+Y)-3(X-Y)=7,2(X+Y)+(X-Y）=-7}则(X+Y)(X-Y)= 已知实数x.y满足根号(x+y-8)+根号(8-x-y)=根号(3x-y-4)+根号(x-2y+7),求x,y 已知x-y/x+y=3,求代数式5(x-y)/x+y-x+y/2(x-y) 已知｛3x+2y=3 2x+3y=7 ,则x+y= ,x-y= 已知7x+5y/2y-x=3/2,且x≠0,求X/x-4y 已知|x|=2,|y|=3,|x+y|=-(x+y)求x-y 已知x-y=3,求[（x+y)(x-y)-(x-y)^2+2y(x-y)]除以的值 已知3x =2y 求x/x+y+y/x-y-y²/x²-y² 已知关于方程2x-3y=7,求3(y-7)-6(x-y) 1、已知x/y=7/2,求x/x+y 2、已知x/2=y/3=z/4,求x+y+z/2x+3y-z!1、已知x/y=7/2,求x/x+y2、已知x/2=y/3=z/4,求x+y+z/2x+3y-z! 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