x²-xy-2y²=0如何让化简

x²-2xy+y²分之x²+2xy-3y³如何因式分解 已知x²-7xy+12y²=0求x²-xy+y²/2xy的值 X²+2xy+y²/xy乘x²-2xy+y²/xy+y²= 若x+2y=0,xy不等于0,求分式x²+2xy/xy+y²的值 已知实数xy满足x²﹢y²-xy+2x-y+1=0求xy 已知X²+Y²+X²Y²-4XY+1=0 求:（X-Y)^2008-(XY)^2 已知(x+1)²+|y-1|=0,求2(xy-5xy²)-(3xy²-xy)得值 已知x²+y²-2x+4y+5=0,求X^4-y^4/2x^2+xy-y²·2x-y/xy 已知2X-3√xy-2y=0(x>0)求2x²+xy-9y²分之x²+4xy-16y
2x+y=0,求4x²+2xy(x+y)+y³ 解方程组:x²+2xy+y²=1 2x²-xy=0 已知x²-3xy+4x=3,y²+xy-4y+7=0,则xy-1/2(x²+y²