If A and B are m × n matrices then have the same rank, then the rank of AB must equal the rank of BA.
举一反三
- Let A be an m×n matrix, then ( ). A: AAT =ATA. B: if rank(A) = m, then AT A is invertible. C: if rank(A) = n, then AAT is invertible. D: if rank(A) = n, then AT A is invertible.
- Which countries rank the same in the survey?
- 以下语句错误的是() A: LECT rank, AVG(salary) FROM people HAVING AVG(salary) > 1000 GROUP BY rank; B: SELECT rank, AVG(salary) FROM people GROUP BY rank HAVING AVG(salary) > 1000 C: SELECT rank, AVG(salary) FROM people HAVING AVG(salary) > 1000 GROUP BY rank; D: SELECT AVG(salary) FROM people GROUP BY rank HAVING AVG(salary) > 1000; E: SELECT rank, AVG(salary) FROM people GROUP BY rank WHERE AVG(salary) > 1000;
- The lowest naval officer rank is ______ , while the lowest army officer rank is ______ .(全部小写)
- 17. A precedent is considered “binding” on a court only if it was decided by that same court or by an appellate court of higher rank in the same jurisdiction.