xy-y=2x+2 x=(2+y)/(y-2)

f(xy,x-y)=x^2+y^2+xy;f(x,y)/∂x;f(x,y)/∂y 已知x*x-4xy+4y*y=0 求[2x(x+y)-y(x+y)]/(4x*x-4xy+y*y)的值? (-x+2y)(2x+y)-(2x+y)(y-2x)-3xy=?因式分解 x*x+xy=3,xy+y*y=2,则x*x+2xy+y*y=________? f(x+y,x-y)=(x^2-y^2)/2xy,求f(x,y)! x+y=-3 xy+x+y=-2 x/y+y/x=? 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 函数f(xy,x+y)=x^2+xy+y^2,则df(x,y)=? f(xy,x-y)=x^2+3xy+y^2,则f(x,y)=? (x+y)^2/y^2-xy÷[-y^2+xy/(x-y)^2,x=0,y=根号10 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xy=-2,x-y=3,求（x+y)（x-y)-y^2+（x-y)^2-（6x^2y-2xy^2)÷2y 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：x(x-50y)+xy=50y^2,求：(x-y):y=?