解题方法
1 . 设数列
、
的前n项和分别为
、
,若
,
,
,则下列4个结论中,正确结论的个数是______ 个.
①
;
②
;
③无论实数m取何值,直线
恒过定点
;
④椭圆
的两个焦点分别为点
、
,点P为椭圆上的任意一点,则
的周长与
的值相同.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/83cf38189d5cbf627d2b82ac0eb76006.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/034ba25825c13725931c483aa47c9363.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/08eb71ecf8d733b6932f4680874dbbf3.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f1ae9a3b0b7aeb1545b65d91aa371b3c.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/fe98dae6e275a3b14a20ee5cabc77165.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9c3a8343b8b6ff765681e7b93e6c28f5.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b5a70e556387e31472b493faa331f0ce.png)
①
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/8569915a8c010b9ee6ace39ca9fc925a.png)
②
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/1a9dd66e01a5b86179f63085fa2da761.png)
③无论实数m取何值,直线
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/8327e623be36ea9b1831530e36398d98.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0b10c99659501287b44db33253e3ddcc.png)
④椭圆
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/cbd56e68f760f146bb4de048a58357df.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f5076289823db419f94e9c0c8f4aafd9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a3fb78c5f885034612c0e030b920143d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/33d776753746914c2410a3946c357f35.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ae0fcf02ab751cc3910a0bc0872ac2a7.png)
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