名校
1 . 已知集合
,
.
(1)求
;
(2)判断
是
的什么条件.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/80551586bd2f13a9b3ac8186f6a9e0a4.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/810fcf0caa1de2ecd142274b7a9587b2.png)
(1)求
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7ae1567d8f98fabc1a3948f8602cc5e7.png)
(2)判断
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/cde2827722685b8a71f9aae2dc4d7484.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e23af61cd402b3789af2401bde9cbefe.png)
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解题方法
2 . 证明“0≤a≤
”是“函数f(x)=ax2+2(a-1)x+2在区间(-∞,4]上为减函数”的充分不必要条件.
![](https://img.xkw.com/dksih/QBM/2016/1/7/1572423988895744/1572423994974208/STEM/e34d4656b68b433b8596affbe90ba472.png)
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