線性代數矩陣證明問題

2011-10-08 3:50 am
Prove that if A is an invertible matrix and B is row equivalent to A,then B is also invertible.

(Matrices A and B are said to be row equivalent if either can be obtained from the other by a sequence of elementary row operations.)
更新1:

感謝,請來領點數

更新2:

還有一題 Let Ax=0 be a homogeneous system of n linear equations in n unknowns that has only the trivial solution.Show that if k is any positive integer,then the system (A^k)x=0 also has only the trivial solution.

回答 (3)

2011-10-18 7:54 am
✔ 最佳答案
其實你把B轉一轉就會變成A了

就像
12
34

13
24
你頭轉一轉就會知他們是一樣的東西

2011-10-17 23:58:25 補充:
剛剛那例子怪怪的
不過以3x3為例

要求determine....你會計算出6個項目
B與A的項目都是相同
所以兩者determine一樣
2011-10-08 5:31 am
B is row equivalent to A iff.
for a sequence of elementary matrices E1,...,En,
B = (En)...(E1)A.
So B^{-1} = A^{-1}(E1)^{-1}...(En)^{-1}.

2011-10-14 20:30:52 補充:
Ax = 0 has only the trivial solution, means that A is full rank,
or equivalently, A is nonsingular.
Therefore, for any positive integer k, A^k is nonsingular too.
Then, A^k X = 0 has only the trivial solution.
2011-10-08 5:29 am
Elementary matrix


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