x^2-y^2=xy 求x/y,

f(x+y,x-y)=(x^2-y^2)/2xy,求f(x,y)! 正数x,y满足x-y=2xy,求x-y/x+y的值. f(x+y,x-y)=2xy(x-y),求f(x,y) x^2+xy+x=36,y^2+xy+y=20,求x+y. 若x^2+xy+y=14,y^2+xy+x=28,求x+y 如果x^2+xy+y-14,y^@+xy+x=28,求x+y的值. f(xy,x-y)=x^2-xy+y^2.求f(x,y) 已知x*x-4xy+4y*y=0 求[2x(x+y)-y(x+y)]/(4x*x-4xy+y*y)的值? x^2-y^2=xy 求x/y, x+y+2xy=83求x+y=? 若1/x-1/y=2,求3x-2xy-3y/x-xy-y的值3x-2xy-3y/x-xy-y 不好意思，是3x-2xy-3y/x-2xy-y y'=-2xy;求f(x). x-2+y=100求Xy 已知：x(x-50y)+xy=50y^2,求：(x-y):y=? 已知x-2y=0,求(x/y-y/x)乘xy/x^2-2xy+y^2 x^2+xy=12,xy+y^2=15,求(x+y)^2-(x+y)(x-y) 已知x+y=-1,xy=-2,求代数式-5（x+y)+(x-y)+x(xy+y)的值 已知,x²+xy=14,y²+xy=2(x>y>0)求x+y.x-y