，其中a＝－2，b＝
．
········································· 2分
····················································································· 3分
································································································ 
4分
= 
························································· 5分
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的值為0，則x的值為 .
其中
．
，其中x是一元二次方程
的正數根.
，則k的值是 2或﹣1 ．
，其中
，則
的值為（ ）
，其中
.
＝___________．