xy=1,y=1/2-根号3,求x2-xy+y2的值.
已知x2-3xy-4y2的绝对值+2倍根号x2+4xy+4y2-1=0 求3x+6y的值
已知x+y=4,xy=2,求x2+y2+3xy的值.
已知2x=3y,求xy/(x2+y2)-y2/(x2-y2)的值
x(x-1)-(x2-y)=-3,求x2-y2-2xy的值
x(x-1)-(x2-y)=-3,求x2+y2-2xy的值
已知x(x-1)-(x2-y)=-3,求x2+y2-2xy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=-3,xy+y2=7,试求:x2+2xy+y2的值.
已知x2;+xy=3,xy+y=-2,求代数式2x2;-xy-3y2;的值
设x,y为实数,且x2+xy+y2=1,求x2-xy+y2的值的范围
已知x(x-1)-(x2-y)=-3,求x2+y2-2xy的值.