对线性方程组的增广矩阵做初等行变换可得 则当（　）时，该方程组有唯一解．

<img src、"http://oss.ouchn.cn/ddzx/N601/gongxue/jjsx/img/3-3/image098.png" alt="" align="middle">

<img src、"http://oss.ouchn.cn/ddzx/N601/gongxue/jjsx/img/3-3/image098.png" alt="" align="middle">且<img src="http://oss.ouchn.cn/ddzx/N601/gongxue/jjsx/img/3-3/image099.png" alt="" align="middle">

<img src、"http://oss.ouchn.cn/ddzx/N601/gongxue/jjsx/img/3-3/image098.png" alt="" align="middle">且<img src="http://oss.ouchn.cn/ddzx/N601/gongxue/jjsx/img/3-3/image100.png" alt="" align="middle">

<img src、"http://oss.ouchn.cn/ddzx/N601/gongxue/jjsx/img/3-3/image101.png" alt="" align="middle">