已知x²-xy,xy-y²=－12,分别求式子x²-y²与x²-2xy

已知x²-xy,xy-y²=－12,分别求式子x²-y²与x²-2xy 已知x²-xy=21,xy-y²=-12,分别求式子x²-y²与x²- 已知x:y=3:2,求(x²+3xy)/(xy+2xy) 已知x²-7xy+12y²=0求x²-xy+y²/2xy的值 已知x/y=3,求(x²+2xy-3xy²)/(x²-xy+y²) 计算：(xy-x²)×x-y/xy x/xy-y²与y/x²-xy 通分 已知实数xy满足x²﹢y²-xy+2x-y+1=0求xy 已知2x-y=10,求式子[(x^2+y^2)-(x-y)^2+2y(x-y)]/4y (4xy-2y²)/4 已知(x+1)²+|y-1|=0,求2(xy-5xy²)-(3xy²-xy)得值 已知y=2x,求(x²-xy-2y²)分之(x²+2xy+y²) 已知x/y=3,求x²+2xy-3y²/x²-xy+y²