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+y2=7,xy=-2.求7x2-3xy-2y2-11xy-5x2+4y2的值.
已知x2+y2 =7,xy=-2.求5x2 -3xy-4y2 -11xy-7x2 +2y2
已知x2+xy=-3,xy+y2=7,试求: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
已知2x=3y,求xy/(x2+y2)-y2/(x2-y2)的值
已知x2-xy=-3,2xy-y2=-8,求2x2+4xy-3y2的值.
已知x2-xy=3,xy-y2=-5,试求代数式x2+2xy-3y2的值.
已知x2-xy=7,2xy+y2=4,则代数式x2+xy+y2的值是___.
已知x2+xy=4,xy+y2=12,求代数式x2-y2与x2+2xy+y2的值各为多少
已知:x=3,y=-5,x2-2xy+y2/x2-y2的值是