x/2=y/3求7x^2-y^2/x^2-2xy+3y^2

已知x-y/x+y=3,求代数式5(x-y)/x+y-x+y/2(x-y) 已知：2x+y=6,x-3y=1 求7y(x-3y)(x-3y)-2(3y-x)(3y-x) 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 若2/x-1/y=3,求[y/x-y/x-y(x-y/x-x+y)]/x-2y/x的值 x+2y=2x+y+1=7x-y 求：2x-y? x^2+y^2=15,x+y=7,x＞y,求x-y 已知|x|=2,|y|=3,|x+y|=-(x+y)求x-y (x-y)/(x+y)=3求( 3x-2y-1)/(x+y-5) y=3(x-y),x=2(x-y)求x,y的值 x-y/x-x+y/y-(x+y)(x-y)/y² y/x=2 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2y-x=-3,求[4y(2x-y)-2x(2x-y)]/(2x-y x+y/2+ x-y/2=6 2(x+y)-3x+3y=24 求X Y {(x+y)/2+(x-y)/3=1,(x+y)-5(x-y)=2.求x=?,y=? 若x-y=2(x+y),求代数式x-y/x+y+x+y/x-y求代数式 x+y分之x-y+x-y分之x+y 已知:y=ax的3次方+bx+3,当x=-1/2时,y=-7,试求x=1/2时,y的值 2X-3Y=3 3X-2Y=7 求X和Y