已知x+y=a,2x-y=-2a,求[(x/y-y/x)/(x+y)-x(1/x-1/y)]/[(x+1)/y]的值
已知4x=9y求(1)x+y/y (2)y-x/2x
1、x(x-y)(x+y)-x(x+y)^2
已知实数x,y满足(x+y)^2=1,(x-y)^2=25,求x,y的值
已知x+y=-1,xy=-2,求代数式-5(x+y)+(x-y)+x(xy+y)的值
已知x,y满足y^4+2x^4+1=4x^2y,求x,y的值
已知3x-4y/2x+y=1/2 求x/y的值
已知|2x-3y|+|3x-y-1|=0,求x,y的值.
已知x=3分之1,y=二分之一,求代数式x-(x+y)+(x+2y)-(x+3y)+...-(x+13y)的值
已知x=1/3,y=-1/2,求代数式x-(x+y)+(x+2y)-(x+3y)+(x+4y)-(x+5y)+...-(
已知x²+y²+5=2x+4y,求【2x²-(x-y)(x-y)】【(x+y-1)(x-y
已知x*x-4xy+4y*y=0 求[2x(x+y)-y(x+y)]/(4x*x-4xy+y*y)的值?
已知2/x+2/y=根号24,求 x/y(x-y) - y/x(x-y)的值