搜题请搜索小程序“爱下问搜题”
问题 问答题

设A是m×n矩阵，对矩阵A作初等行变换得到矩阵B，证明矩阵A的列向量与矩阵B相应的列向量有相同的线性相关性．

答案

参考答案：因经初等行变换由A可得到B，故存在初等矩阵P1，P2，…，Ps使Ps…P2P1A=B．
对矩阵A，B按列分块，并记A=(α1，α2，…，αn)， B=(β1，β2，…，βn)，P=Ps…P2P1，则有P(α1，α2，…，αn)=(β1，β2，…，βn)．
于是Pαi=βi(i=1，2，…，n)．
A的列向量[*]线性相关，

解析：评注 由于A的列向量中相应的列向量有相同的线线性相关性，这就为我们求向量组的秩与极大线性无关组提供了方法．
[*]

阅读理解

阅读理解。

      I am Alice. Today the clothes at Beauty Clothes Store are on sale. So I want to buy some clothes

for my grandparents, my parents and myself.  Let me have a look.  This yellow sweater is at a very good

price-only 15 dollars. And it's OK for my grandfather. For my grandmother,1 want to buy these black

shoes. They are comfortable(舒适的)．

     How about this white T-shirt? Oh, my father can wear(穿)it for playing basketball. And there are many socks in green, yellow, black, red and white.I know my mother likes red very much, s0 1 will buy the red ones.  I need pants, so I'Il take these blue one.

根据短文内容，完成下列句子。

1. Iwant to buy a yellow_____for my grandfather.

2. My mother like_____very much.

3. I'll buv black shoes for my_____.

4. My father can wear a white_____for playing basketball.

5. I'll take _____ pants for myself.
查看答案
判断题

当ADC208复印身份证或小原稿（不是标准尺寸）二合一中间有黑线，四合一有十字黑线，其它A3/A4/A5原稿没有问题，则需要在：维修模式→Machint Adjustment→lead edge erase adjustment→把默认“4毫米”改成“5毫米”或“6毫米”。
查看答案