x+y=-2 x+y=4 求x^2-y^2的值

x-y/x-x+y/y-(x+y)(x-y)/y² y/x=2 如果|X|=4 |Y|=2 且|X+Y|=X+Y 求X+Y 2x-y=2,求[(x²+y²)-(x-y)²+2y(x-y)]÷4y 已知x*x-4xy+4y*y=0 求[2x(x+y)-y(x+y)]/(4x*x-4xy+y*y)的值? 已知2y-x=-3,求[4y(2x-y)-2x(2x-y)]/(2x-y 已知x/y=2,求2x(x+y)-y(x+y)/4x²-4xy+y² 已知x-y/x+y=3,求代数式5(x-y)/x+y-x+y/2(x-y) 若(x*x+y*y)(x*x+y*y)-4x*x*y*y=0,求代数式(x*x+5xy+y*y)/(x*x+2xy+y*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)]除以y的值大神们帮帮忙 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=3,求[（x+y)(x-y)-(x-y)^2+2y(x-y)]除以的值 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3x =2y 求x/x+y+y/x-y-y²/x²-y² y*y*y*y+2x*x*x*x=4x*x*y 求x等于几,y等于几,写出所有选项! 已知(x+2y)(2x-3y)=y(y-4x),试求x/y的值 y=2x*arctan(y/x),求y‘’ (x-y) (x-2y)+(x+2y) (x-3y)-2(x-3y) (x-4y)=