x²+y²+4x-8y+20=0,求(x²-y²)÷xy的解

x²+y²+4x-8y+20=0,求(x²-y²)÷xy的解 x²+y²+4x-8y+20=0,求分式x²-y²/xy的值 已知x²+y²=3xy且xy≠0,求x²y－²+x－²y²的 已知x²y²+x²+y²=10xy-16 求x,y 已知X²-5XY+6Y²=0,求(X²+3XY)\2Y²的值 |x+2y+3|+(2x+y)²=0求x²-xy+y² 若x² +xy+y² =14,x² -xy+y²=28求x+y的值 若x²+xy+y²=14,x²-xy+y²=28,求x+y的值 已知x/y=3,求x²+2xy-3y²/x²-xy+y²的值 已知xy=8满足x²y-xy²-x+y=56,求x²+y² x²-4y²/x²+2xy+y²÷x+2y/2x²+2xy 已知3x+2y=0,求代数式(x²+xy-y²)÷(x²-xy+y²)的值.