已知x,y满足x2/9+y2/4=1,则xy的取值范围是?
已知x,y满足x2/9+y2/4=1,则xy的取值范围是?
设实数x,y满足x2+y2=1则 xy的取值范围是?
已知实数xy满足x2+y2-4x+3=0则(x+y-3)/(x-y+1)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______.
已知实数xy满足x2+y2=4.则y+3/x+1的取值范围为
已知实数XY 满足X2+Y2=1,求Y+2/X+1的取值范围
设实数xy满足x2 +2y2=6,则x+y的取值范围
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=4,求x+y的取值范围
已知x,y∈R,且1≤x2+y2≤2,z=x2+xy+y2,则z的取值范围是
已知函数x,y满足x2+y2=2x,则x2+y2的取值范围
已知实数x.y满足x2+y2=4.则3x+4y的取值范围是