1 . 以下四个关于圆锥曲线的命题中:
①设
为两个定点,
为非零常数,
,则动点
的轨迹为双曲线;
②过定圆
上一定点
作圆的动弦
,则弦
中点P的轨迹为椭圆;
③方程
的两根可分别作为椭圆和双曲线的离心率;
④双曲线
与椭圆
有相同的焦点.
其中真命题的序号为__________ .(写出所有真命题的序号)
①设
![](https://img.xkw.com/dksih/QBM/2015/12/17/1572368410738688/1572368416661504/STEM/050844625d53490eaca84cd88a24bcf1.png?resizew=32)
![](https://img.xkw.com/dksih/QBM/2015/12/17/1572368410738688/1572368416661504/STEM/9a8f29a11fe44335ad2fcedbf2e2d8f1.png?resizew=13)
![](https://img.xkw.com/dksih/QBM/2015/12/17/1572368410738688/1572368416661504/STEM/761223df1fd84f72a5a5c8d812e3d2e1.png?resizew=104)
![](https://img.xkw.com/dksih/QBM/2015/12/17/1572368410738688/1572368416661504/STEM/85db808d7db742699aac6ba16653787b.png?resizew=16)
②过定圆
![](https://img.xkw.com/dksih/QBM/2015/12/17/1572368410738688/1572368416661504/STEM/1f3d2c2126bf4f2299f22418acff701e.png?resizew=16)
![](https://img.xkw.com/dksih/QBM/2015/12/17/1572368410738688/1572368416661504/STEM/710a5b7c41574fe6a8e75c59e0a9d1b6.png?resizew=16)
![](https://img.xkw.com/dksih/QBM/2015/12/17/1572368410738688/1572368416661504/STEM/7ac2966eed4f420bbc5bb9e5abd97e81.png?resizew=27)
![](https://img.xkw.com/dksih/QBM/2015/12/17/1572368410738688/1572368416661504/STEM/7ac2966eed4f420bbc5bb9e5abd97e81.png?resizew=27)
③方程
![](https://img.xkw.com/dksih/QBM/2015/12/17/1572368410738688/1572368416661504/STEM/c58d3114372e49de9d82d53045d59086.png?resizew=107)
④双曲线
![](https://img.xkw.com/dksih/QBM/2015/12/17/1572368410738688/1572368416661504/STEM/7edcde3be3024e0e815a1c9463e6e84f.png?resizew=80)
![](https://img.xkw.com/dksih/QBM/2015/12/17/1572368410738688/1572368416661504/STEM/5badc90302224606bed492a05b7eeecb.png?resizew=76)
其中真命题的序号为
您最近一年使用:0次
名校
2 . 在对吸烟与患肺病这两个分类变量的独立性检验中,下列说法正确的序号是( )(参考数据:P(K2≥6.635)=0.01)
A.若K2的观测值满足K2≥6.635,我们有99%的把握认为吸烟与患肺病有关系. |
B.若K2的观测值满足K2≥6.635,那么在100个吸烟的人中约有99人患有肺病. |
C.从独立性检验可知,如果有99%的把握认为吸烟与患肺病有关系时,那么我们就认为:每个吸烟的人有99%的可能性会患肺病. |
D.从统计量中得知有99%的把握认为吸烟与患肺病有关系时,是指有1%的可能性使推断出现错误. |
您最近一年使用:0次