4x2-3y2+2xy-4x2+5x2

4x2-3y2+2xy-4x2+5x2 (x2+xy+y2)-4xy(x2+y2) 4x2+3xy-2y2因式分解 计算(x+y/x-y + 4xy/y2-x2)(x2-9y2)/（x2+2xy-3y2） 若3x2-4xy+y2=-3,2x2+3xy-2y2=8,求5x2-18xy+7y2的值. 已知x2+y2=7,xy=-2,求5x2—3xy—4y2—11xy—7x2+2y2的值 5x2-3xy-4y2-11xy+(-7x2)-(-2y2),其中x2+y2=7,xy=-2,求值 已知X2+y2=7,Xy=-2,求多项式5X2一3Xy-4y2-11Xy-7X2+2y2的值. 已知x2+y2 =7,xy=-2.求5x2 -3xy-4y2 -11xy-7x2 +2y2 (2x2-3xy+4y2)+(x2+2xy-3y2）化简（要有过程） 4x2-y2/x2-2xy+y2 +(2x-y)/2x2-2xy x2+y2+2xy=256 x2+y2-2xy=4 (x2, (x2-y2)-4(2x2-3y) (x2+xy+y2)-4xy(x2+y2)因式分解 已知:x2+y2=7,xy=-2.求7x2-3xy-2y2-11xy-5x2+4y2已知:x2+y2=7,xy=-2.求7x2-3xy-2y2-11xy-5x2+4y2 已知x2+y2+4x-2y+5=0,求x2+2xy+y2值 x2-4y2-3xy+y+x x2+3xy-4y2因式分解