已知实数x,y满足x2+y2-4x+1=0,求2x+y的取值范围?

已知实数x,y满足x2+y2-4x+1=0,求2x+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 已知实数x,y满足x2+y2+4x+3=0,求（y-2）／（x-1）的取值范围. 已知实数x,y满足x2+y2+4x+3=0,求x-1分之y-2的取值范围 已知实数x，y满足：x2+3y2-3=0，求x+y的取值范围． 实数x,y 满足x2+y2-2x-4y+1=0,求y/(x+2)的取值范围 已知实数x y满足方程x2加 y2-2x加4y等于0,求x减2y的取值范围! 已知实数XY 满足X2+Y2=1,求Y+2/X+1的取值范围 已知a>0,实数x,y,z满足x+y+z=a,x2+y2+z2=a2/2,求x的取值范围 已知实数x,y,z满足以下条件,求x的取值范围.x+y+z=a,x2+y2+z2=1/2 a2 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xy满足x2+y2-4x+3=0则(x+y-3)/(x-y+1)的取值范围是