设x(x-1)-(x2-y)=-2,求(x2+y2\2)-xy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
设x,y为实数,且x2+xy+y2=1,求x2-xy+y2的值的范围
已知x-y+1,X2+Y2=25 求(x+y)2和x2-xy+y2的值
若X2+Y2-2X-6Y+10=0 ,求(x2-y2)/xy的值
当x=2,y=1 求{(x2+y2)/(x2-2xy+y2)+(2)/xy÷[(1/x)-(1/y)]}÷(x+y)的值
若x2-2xy-y2-x+Y-1=0 求x-y的值
(x+y)(x+y+1)=0 求x2+y2+2xy的值
正数xy满足x2-y2=2xy,求x+y分之x-y的值
已知x2+y2=20,x2+xy-2y2=2(x+2y),求x+y的值