已知x2-xy=-3,2xy-y2=-8,求 (1)x2+xy-y2 (2)2x2+4xy-3y2 字母后面直接跟数字的
已知x2-xy=-3,2xy-y2=-8,求2x2+4xy-3y2的值.
已知2x=3y,求xy/(x2+y2)-y2/(x2-y2)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-xy=3,xy-y2=-5,试求代数式x2+2xy-3y2的值.
已知x2+xy=-3,xy+y2=7,试求:x2+2xy+y2的值.
已知x2+y2 =7,xy=-2.求5x2 -3xy-4y2 -11xy-7x2 +2y2
已知2x2+xy=6,3y2+2xy=9,求4x2+8xy+9y2的值为______.
已知x2+xy=3,xy+y2=-2,则2x2-xy-3y2的值为( )
已知X2次方+XY=3,XY+Y2次方=-2,求下例值:X2次方-Y2次方
已知:x2+y2=7,xy=-2.求7x2-3xy-2y2-11xy-5x2+4y2已知:x2+y2=7,xy=-2.求