代数式x2-2xy+3y2-2x-2y+3的值的取值范围是 ______.
已知x、y是实数且满足x2+xy+y2-2=0,设M=x2-xy+y2,则M的取值范围是______.
若实数x,y满足2x2+3y2=1,S=3x2-2y2,则S的取值范围是______.
设x,y≠0,且方程(x2+xy+y2)a=x2-xy+y2成立,则实数a的取值范围是______.
实数x、y满足x2+xy+y2=2,记u=x2-xy+y2,则u的取值范围是
已知实数x,y满足x2+y2=2x,则x2y2的取值范围是______.
设实数xy满足x2 +2y2=6,则x+y的取值范围
已知:x=3,y=-5,x2-2xy+y2/x2-y2的值是
x、y是自然数,x2+2xy+4y2=6,则x2+4y2的取值范围是 ( ) 请教详细解答过程,
已知2x=3y,求xy/(x2+y2)-y2/(x2-y2)的值
已知x,y∈R,且1≤x2+y2≤2,z=x2+xy+y2,则z的取值范围是
设x,y是实数,且 x2+xy+y2=3.那么,x2-xy+y2的取值范围是?
若实数X,Y,满x2+xy+y2=3,则x2+y2的取值范围