1 . 下列五个命题,其中正确命题的个数为( )
①已知
,则![](https://staticzujuan.xkw.com/quesimg/Upload/formula/315c84dc5c31e1ec58b0957a24caf400.png)
②过原点作直线
的切线,则切线方程为![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c603ebebcc2551c4c58a4b1758ed1ad1.png)
③已知随机变量
,且
,则![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4effc9159da3fff945e127842f9836bd.png)
④已知
为正整数,用数学归纳法证明等式
时,若假设
时,命题为真,则还需利用归纳假设再证明
时等式成立,即可证明等式对一切正整数
都成立
⑤在回归分析中,常用
来刻画回归效果,在线性回归模型中,
表示解释变量对于预报变量变化的贡献率,
越接近1,表示回归的效果越好
①已知
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/978c9adecf65391ace71f8157368cb8c.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/315c84dc5c31e1ec58b0957a24caf400.png)
②过原点作直线
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9f2eff609c6043c2a89a6dd163fe2244.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c603ebebcc2551c4c58a4b1758ed1ad1.png)
③已知随机变量
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e8b891ec9d9abbb7ffaa6d1ad01978a1.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9500cfe7f5ca2b282c258734534e4d36.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4effc9159da3fff945e127842f9836bd.png)
④已知
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b6a24198bd04c29321ae5dc5a28fe421.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0a7f91d2a8c6a2089372c66069664e98.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ac31dc10e8978562277e84eb9daa923f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/63ba21f3d0cfc86d40e2e06446623ce0.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b6a24198bd04c29321ae5dc5a28fe421.png)
⑤在回归分析中,常用
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4c85067c53e936ef32da818efe04bdbb.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4c85067c53e936ef32da818efe04bdbb.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4c85067c53e936ef32da818efe04bdbb.png)
A.2 | B.3 | C.4 | D.5 |
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2 . 已知
.若曲线
在点
处的切线过坐标原点,则![](https://staticzujuan.xkw.com/quesimg/Upload/formula/bffd29b2e8192d673308bdf8d5cb6cab.png)
___________ ;若命题“对
,
恒成立”为假命题,则k的一个值可以是___________ .
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6ff6838d84b68c6f0d3b93b196d9b08d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/942c2141d01bde6b48210c56a17fc75e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/43db00e106c7d08a76a7ba71ca5e63d1.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/bffd29b2e8192d673308bdf8d5cb6cab.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d96b743603ab1c10330622f16db78dbe.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/dde411d48babb7440973862b0e9bd017.png)
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