已知x=3+1,y=3-1,则2x2-3xy+y2的值为( )
已知2x=3y,求xy/(x2+y2)-y2/(x2-y2)的值
已知x(x-1)-(x2-y)=-3,求x2+y2-2xy的值
已知x2-2xy=3y2且x,y为非零实数 求:(1)2x+y/x-2y (2)2x2-3y2+5xy/x2+xy+y2
已知:x=3,y=-5,x2-2xy+y2/x2-y2的值是
已知实数x,y满足x2+xy+y2=3,则x2-xy+y2的最小值
已知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x2+xy=3,xy+y2=-2,则2x2-xy-3y2的值为( )
已知(x-y+1)2+|2x+y-7|=0.则x2-3xy+2y2的值为( )
已知xy=9,x-y=-3,则x2+3xy+y2的值为( )
已知x+y=4,xy=3求(1)x2=y2 (2)x-y的值
已知实数xy满足x2+y2=4.则y+3/x+1的取值范围为