-2xy-x2-y2要过程

-2xy-x2-y2要过程 x2-3y2=2xy过程 解方程组：｛x2+y2=13,x2-2xy+y2=1要完整过程！！！~~ (2x2-3xy+4y2)+(x2+2xy-3y2）化简（要有过程） x2-2xy-3y2分解因式要有过程 (x2+2xy+y2)( x2-xy+y2)2 化简 (x2-2xy+y2)-(x2+2xy+y2)=什么 ( x2+xy+y2) ( x2+xy+2y2)-12y4 x2-2xy+y2-9 计算：(xy-x2)÷xy分之x2-2xy+y2 求证:(x2-xy+y2)3+(x2+xy+y2)3能被2x2+2y2整除 若X2+xy-2y2=0,则（x2+3xy+y2)/x2+y2=? (x2+y2)(x2-xy+y2)-2x2y2因式分解 (x2+xy+y2)-4xy(x2+y2) 4x2-3y2+2xy-4x2+5x2 2(x2-xy)-3(2x2-3xy)-2[x2-(2x2-xy+y2)] 化简. 4x2-y2/x2-2xy+y2 +(2x-y)/2x2-2xy 已知x2+xy=3,xy+y2=-2,则2x2-xy-3y2=