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=4.则y+3/x+1的取值范围为 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 设实数xy满足x2 +2y2=6,则x+y的取值范围 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=1,求Y+2/X+1的取值范围 已知实数x,y满足x2+xy+y2=3,则x2-xy+y2的最小值 已知实数x.y满足x2+y2＝4.则3x+4y的取值范围是 已知实数x,y满足x2+2xy+3y2-8y+6=0,求x,y的取值范围 已知实数x,y满足x2+y2=4,求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x,y满足x2/9+y2/4=1,则xy的取值范围是?