<p>设矩阵<i>A=<img src="https://file.gaojiufeng.cn/learnAppQuestion/b2/aa/b2aabf62dc87d30558f4ad626ed1c6c8.jpg" style="width: 100%;height: auto;">，B=<img src="https://file.gaojiufeng.cn/learnAppQuestion/34/1e/341ea358d4110df144bc17a4c31c2cc3.jpg" style="width: 100%;height: auto;">，且r(<i>A)=1，则r（<i>B）=_____