解题方法
1 . 从数字1,2,3,4,5中取两个不同的数字,设“两个数字之和为偶数”为事件
,则事件
的概率为______ .
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5963abe8f421bd99a2aaa94831a951e9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5963abe8f421bd99a2aaa94831a951e9.png)
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2 . 把一个容量为
的样本分成若干组,若某组的频数和频率分别为9和0.15,则
的值为______ .
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b6a24198bd04c29321ae5dc5a28fe421.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b6a24198bd04c29321ae5dc5a28fe421.png)
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3 . 已知函数
满足
,且
,则![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5a220e516e0f51cf9132c05a2ba3ec05.png)
______ .
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/09f86f37ec8e15846bd731ab4fcdbacd.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/1e6cb3385b59bdc10be5748d84674abd.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/3359f013aac2768a0c54cae1a95a158c.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5a220e516e0f51cf9132c05a2ba3ec05.png)
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解题方法
4 . 若正数
、
、
满足
,则式子
的最小值为______ .
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0a6936d370d6a238a608ca56f87198de.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2c94bb12cee76221e13f9ef955b0aab1.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/071a7e733d466949ac935b4b8ee8d183.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9d4006ac61d0c2e90d99d4b1fa9653eb.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e7c2cadc9861f4aa411006477be030a3.png)
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