已知x^2-y^2=27,x-y=3,求y/x的值

已知x^2-y^2=27,x-y=3,求y/x的值 已知2/x+2/y=根号24,求 x/y(x-y) - y/x(x-y)的值 已知2/x 2/y=根号24,求 x/y(x-y) - y/x(x-y)的值 已知X-Y/X+Y=3,求代数式2(x-y)/X+Y-3X+Y/X+Y 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/x+2y=3,求2(2x-y)/x+2y-9(x+2y)/2x-y+3的值. 已知x+y分之x-y=2,求2x+2y分之x-y-3x-3y分之2x+2y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分之x-y=2 求x+y分之3x-3y 减x-y分之2(x+y)的值 已知x-y/x+y=2,求代数式2(x-y)/x+y + x+y/3(x-y)的值 快啊. 已知x-y除以x+y=3,求代数式x+y分之2（x-y)-3(x-y)分之x+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?