证明:
分别对 、A、BA、B 进行初等行变换,使其转化为阶梯型矩阵 、Jra、JrbJ_{ra}、J_{rb}
二者分别有 、ra、rbra、rb (指 、A、BA、B 的秩)行非零行。
![](https://video.ask-data.xyz/img.php?b=https://iknow-pic.cdn.bcebos.com/b64543a98226cffc854cd927ab014a90f703eac5?x-bce-process=image%2Fresize%2Cm_lfit%2Cw_600%2Ch_800%2Climit_1%2Fquality%2Cq_85%2Fformat%2Cf_auto)
具体证明见图片
![](https://video.ask-data.xyz/img.php?b=https://iknow-pic.cdn.bcebos.com/f603918fa0ec08fa9a6675324bee3d6d54fbdac5?x-bce-process=image%2Fresize%2Cm_lfit%2Cw_600%2Ch_800%2Climit_1%2Fquality%2Cq_85%2Fformat%2Cf_auto)
性质:定理一:设 m×nm\times n 矩阵 AA 的秩为 R(A)R(A) ,则 nn 元齐次线性方程组 Ax=0Ax=\textbf{0} 的解集 SS 的秩 RS=n−R(A)R_{S}=n-R(A)
![](https://video.ask-data.xyz/img.php?b=https://iknow-pic.cdn.bcebos.com/6a600c338744ebf8fc1702aacbf9d72a6159a7c5?x-bce-process=image%2Fresize%2Cm_lfit%2Cw_600%2Ch_800%2Climit_1%2Fquality%2Cq_85%2Fformat%2Cf_auto)
3.若 n 元齐次线性方程组 Ax=0 与 Bx=0 同解,则 R(A)=R(B)