y=(x^2-x+3)/x,x∈(-∞，0),求值域

我用了两种方法 两种结果不一样 帮我检查
1.判别式法：xy=x^2-x+3
x^2-x-xy=3=0
x^2-(1+y)x+3=0
则 (1+y)^2-12>=0
|1+y|>=2根号3
y>=-2根号3-1 或 y<=-2根号3-1
第二种 均值不等式法：
y=x+3/x-1
=-[(-x)+3/(-x)]-1
<=-2根号3-1
错在哪了

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