已知X=30,Y=-4,求|X|-|Y|的值.（要写过程）

已知：4x = 5y,求(x+y) ：y 已知:3x-5y=0,求x/y,x-y/y,x-y/x 已知x/y=2,求2x(x+y)-y(x+y)/4x²-4xy+y² 已知2y-x=-3,求[4y(2x-y)-2x(2x-y)]/(2x-y 已知x×x×y×y+x×x+y×y+1=4xy,求x,y的值快 已知5x-4y=0,求x:y和x+y:y的值 已知x*x-4xy+4y*y=0 求[2x(x+y)-y(x+y)]/(4x*x-4xy+y*y)的值? 已知(x+2y)(2x-3y)=y(y-4x),试求x/y的值 已知:【(x²+y²)-(x-y)²+2y(x-y)】/4y=1,求4x/4x²-y²-1/2x+y 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-y/x+y=3,求代数式5(x-y)/x+y-x+y/2(x-y) 已知y=x^y,求dy 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) 已知实数x,y满足方程x*x+y*y-4x+1=0.求y-x的最大值 已知x=y+2,求[(x+y)(x-y)-(x-y)的2次方+2y(x-y)]÷4y的值 已知3x =2y 求x/x+y+y/x-y-y²/x²-y² 已知x-y=3,求[（x+y)(x-y)-(x-y)^2+2y(x-y)]除以的值