2(x2-xy)-3(2x2-3xy)-2[x2-(2x2-xy+y2)] 化简.

2(x2-xy)-3(2x2-3xy)-2[x2-(2x2-xy+y2)] 化简. 2(x-xy)-3(2x2-3xy）2[x2（2x2-xy+y2)] (3xy-9x2-2y2-6xy)-(6x2+2xy-3xy-y) 4x2-3y2+2xy-4x2+5x2 已知x2+xy=3,xy+y2=-2,则2x2-xy-3y2= 求证:(x2-xy+y2)3+(x2+xy+y2)3能被2x2+2y2整除 已知x2-3xy=-5,xy+y2=3,求x2-2xy+y2. 若X2+xy-2y2=0,则（x2+3xy+y2)/x2+y2=? 2x2-xy+3y2因式分解 x2 y2+3xy+2 因式分解 x2-3y2=2xy过程 2X2-3XY-Y2分解因式! 4x2+3xy-2y2因式分解 -（x2-2xy-y2)+(5x2-2xy-3y2)-（x2-2xy-y2)+(5x2-2xy-3y2)化简 计算：(xy-x2)÷xy分之x2-2xy+y2 多项式x2-3xy+2y2-2加上( )等于5x2-7xy-3y2 (2x2-3xy+4y2)+(x2+2xy-3y2）化简（要有过程） 解方程组 x2 -2xy -y2 =1 2x2 -5xy -3y2 =0