已知x/3=y/4,则x-y/4x+3y=

已知2y-x=-3,求[4y(2x-y)-2x(2x-y)]/(2x-y 已知x/3=y/4,则x-y/4x+3y= 已知(x+y)²=4 (x-y)²=3则x²+y² 已知3x-4y=0,则x^2-y^2/x^2+y^2 已知-x+y=3,则2(x-y)2次方-4(x-y)+6 已知二元一次方程x+y=7,3x+4y=19,则x-y=()x+y=() 已知实数x,y满足（x+y)(x+y+3)-4=0则x+y的值是 已知x-y=1,求[(x+2y)²+(2x+y)(x-4y)-3(x+y)(x-y)]÷y的值 已知x-y=1,求[(x+2y)^2+(2x+y)(x-4y)-3(x+y)(x-y)]除以y的值大神们帮帮忙 已知x=3分之一,y=-2分之一,求代数式x-(x+y)+(x+2Y)-(x+3y)+(x+4y)...-(x+2009y) 已知(x+2y)(2x-3y)=y(y-4x),试求x/y的值 已知:3x-5y=0,求x/y,x-y/y,x-y/x 已知x/5=y/3,则(x/x+y)+(y/x-y)-(yxy/xxx-yxy) 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2x-y/x+3y=2,求代数式4x-2y/x+3y减4x+12y除以2x-y 已知2x-y/x+3y=2,求代数式4x-2y/x+3y减4x+12y/2x-y的值 已知2x-y/x+3y=2,求代数式4x-2y/x+3y减4x+12y/2x-y的值 已知x+y=-4试计算多项式0.5(x+y)+4(x-y)-3(x-y)-1.5(x+y)-x+y的值