已知x/y=2/7,求分式x2-3xy+2y2/x2-2xy+y2的值
已知2x=3y,求xy/(x2+y2)-y2/(x2-y2)的值
已知:x=3,y=-5,x2-2xy+y2/x2-y2的值是
已知x(x-1)-(x2-y)=-3,求x2+y2-2xy的值
已知x+y=4,xy=2,求x2+y2+3xy的值.
已知X2-2x+y2+6y+10=0,求(x2-2xy)/(xy+y2)的值
已知(x+y)2=25,xy=3,求x2+y2求x2+y2的值答案是?
已知x2+xy=-3,xy+y2=7,试求:x2+2xy+y2的值.
已知非零实数x,y满足:x2+xy-2y2=0,求(x2+3y+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+y2=20,x2+xy-2y2=2(x+2y),求x+y的值