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,求多项式5X2一3Xy-4y2-11Xy-7X2+2y2的值. 已知x2-3xy=-5,xy+y2=3,求x2-2xy+y2. 已知x2+y2=7,xy=-2,求5x2—3xy—4y2—11xy—7x2+2y2的值 已知x2+y2 =7,xy=-2.求5x2 -3xy-4y2 -11xy-7x2 +2y2 已知X/Y=2/7, 求X2-3XY+2Y2/2X2-3XY+7Y2的值 已知x/y=2/7,求分式(x2-3xy+2y2)/(x2-2xy+y2)的值 已知x/y=2/7,求分式x2-3xy+2y2/x2-2xy+y2的值 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=9,xy=-3,求多项式5x²-3xy-5y²-11xy-8x²+2y² 已知x2+xy=7 y2+xy=2 求x-y的值 已知x2+y2+4x-2y+5=0,求x2+2xy+y2值 已知x2+y2=2,求x2-2xy-y2的取值范围 已知x2+xy=4,xy+y2=12,求代数式x2-y2与x2+2xy+y2的值各为多少格式正确 已知x2+xy=3,xy+y2=-2,则2x2-xy-3y2= 已知A=x2-xy+y2,B=-x2+2xy+y2求A+B A-B 一个多项式与多项式2x2--3xy-y2的差是x2+xy+y2,求这个多项式 已知y/x=1/2,求(x2+2xy+y2)/﹙x2-xy-2y2)的值. 已知X2-2x+y2+6y+10=0,求（x2-2xy）/(xy+y2)的值