1 . 已知
.求证:
三点共线的充要条件是
.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c39d023fc87895b0f26477e890074e3a.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/24e0c10fb103930eabd5fa18e8f9bb06.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7358ff8d99126de46113bb1c1c50f726.png)
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2 . 已知数列
满足条件
,且![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7def23f30138e0b7c4c1e498d6903a6c.png)
(1)计算
,请猜测数列
的通项公式,并用数学归纳法证明;
(2)请分别构造一个二阶和三阶行列式,使它们的值均为
,其中,要求所构造的三阶行列式主对角线下方的元素均为零,并用按某行或者某列展开的方法验证三阶行列式的值为
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/63d471926f7b27322d90c82b9ce21d3d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/78ad02240a394e3a8374377d41a0b753.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7def23f30138e0b7c4c1e498d6903a6c.png)
(1)计算
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/920ad6b9e7f1c2c4a5a3025ba57e71b1.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/63d471926f7b27322d90c82b9ce21d3d.png)
(2)请分别构造一个二阶和三阶行列式,使它们的值均为
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/96abfe2da27a63e6affb19a0c80236d9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/96abfe2da27a63e6affb19a0c80236d9.png)
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3 . 已知方程组![](https://staticzujuan.xkw.com/quesimg/Upload/formula/267ad467cfcbcc2dff5b77665f13a8e2.png)
(1)求证:方程组恰有一解;
(2)求证:以方程的解
为坐标的点在一条直线上;
(3)求
的最小值,并求此时a的范围.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/267ad467cfcbcc2dff5b77665f13a8e2.png)
(1)求证:方程组恰有一解;
(2)求证:以方程的解
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/82a79a33a83a7ba57a34b5093d1d1d02.png)
(3)求
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7dbd4d32dcc1445563887de5d3ab7fb7.png)
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