线性代数题目 求解答过程 谢谢_百度知道
线性代数题目 求解答过程 谢谢
1.A= 第一行1 -1 -1 第二行0 -1 1 第三行0 0 -1 B= 第一行2 1 1 第二行0 1 2 且CA-B=2C 求C （我算出来答案不对，难道是方法错了求过程） 2.假设n1,n2，n3是齐次线性方程组Ax=0的一基础解系，证明向量组n1+n2,n2+n3,n3+n1,也是Ax=0的一基础解系 （这个真不会证明） 神人请助我一臂之力吧 跪谢了
提问者采纳
1.CA-B=2C，所以C(A-2E)=B，之后求出A-2E的逆矩阵，然后用B×(A-2E)^(-1)就是矩阵C。 2.首先证明向量组n1+n2,n2+n3,n3+n1是Ax=0的解， 这很明显，因为A(n1+n2)=0，A(n2+n3)=0，A(n3+n1)=0，所以向量组n1+n2,n2+n3,n3+n1是Ax=0的解。 接下来证明向量组n1+n2,n2+n3,n3+n1线性无关，用反证法， 假设向量组n1+n2,n2+n3,n3+n1线性相关，那么有k1(n1+n2)+k2(n2+n3)+k3(n3+n1)=0， 即(k1+k3)n1+(k1+k2)n2+(k2+k3)n3=0，因为n1,n2,n3是齐次线性方程组Ax=0的一基础解系， 所以有k1+k3=0，k1+k2=0，k2+k3=0，解得k1=k2=k3=0，所以n1+n2,n2+n3,n3+n1线性无关。 所以向量组n1+n2,n2+n3,n3+n1,也是Ax=0的一基础解系。
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出门在外也不愁求解答过程：阅读理解.
When pets get sick,you can usually take them to an animal doctor or an animal hospital.Sometimes
animals are so sick or hurt that you shouldn't move them.That's why Dr.Bird,a
veterinarian
,h_百度作业帮
求解答过程：阅读理解.
When pets get sick,you can usually take them to an animal doctor or an animal hospital.Sometimes
animals are so sick or hurt that you shouldn't move them.That's why Dr.Bird,a
veterinarian
求解答过程：阅读理解.
&&&& When pets get sick,you can usually take them to an animal doctor or an animal hospital.Sometimes
animals are so sick or hurt that you shouldn't move them.That's why Dr.Bird,a
veterinarian
,has a traveling
hospital.Dr.Bird drives his hospital,which is really a van,to the animals. &&&& Dr.Bird has run the hospital for over 10 years,and he has saved the lives of many pets.The van has an
operating table,medicines and everything else he needs to treat animals.Dr.Bird says that there will soon be many more traveling hospitals to help sick or injured animals. 1. The best name is ________. A. Why People Get Sick B. A Traveling Hospital C. Dogs Make Good Pets D. A Very Sick Animal 2. Dr.Bird has run the hospital for ________. A. 12 years B. 10 years C. 8 years D. 20 years 3. The story says that Dr. Bird's hospital has ________. A. thick rugs B. no lights C. toys D. medicines 4. Dr. Bird is ________. A. a&dentist B. an animal doctor C. very young D. very sick 5. The word "veterinarian" means________. A. animal doctor B. nurse C. farmer D. truck driver阅读下面的解答过程，求y2+4y+8的最小值．解：y2+4y+8=y2+4y+4+4=（y+2）2+4≥4，∵（y+2）2≥0即（y+2）2的最小值为0，∴y2+4y+8的最小值为4．仿照上面的解答过程，求m2+m+4的最小值和4-x2+2x的最大值．【考点】．【专题】阅读型．【分析】（1）多项式配方后，根据完全平方式恒大于等于0，即可求出最小值；（2）多项式配方后，根据完全平方式恒大于等于0，即可求出最大值．【解答】解：（1）m2+m+4=（m+）2+，∵（m+）2≥0，∴（m+）2+≥．则m2+m+4的最小值是；（2）4-x2+2x=-（x-1）2+5，∵-（x-1）2≤0，∴-（x-1）2+5≤5，则4-x2+2x的最大值为5．【点评】此题考查了配方法的应用，熟练掌握完全平方公式是解本题的关键．声明：本试题解析著作权属菁优网所有，未经书面同意，不得复制发布。答题：dbz1018老师　难度：0.67真题：3组卷：24
解析质量好中差求解答过程：阅读理解。_百度知道
求解答过程：阅读理解。
阅读理解。
&&&& &In 1961 Obama was born in Hawaii, US. His father was an African and his mother was a white
American. He grew up in Indonesia and Hawaii.
&&&& &When Obama was 10 years old, he was one of the only three black students at his school in Hawaii. He felt very different from most other students. White girls wanted to touch his hair. A white boy even asked him what his father was. &&& &"I lied to them that my father was a Kenyan prince. But I kept asking myself who I am," said Obama.
&&&&& However, 37 years later, the boy made history. Obama became the first black president in US history.& &&&&& This unusual background made him wonder who he was. He once turned to alcohol (酒) to help forget this question.
&&&&& With the help of his friends, Obama finally turned his life around at college. His hard work made him a
star at Harvard. Later, he became the third black senator (参议员) in US history. &&& &"Obama's success has made Martin Luther King's dream come true. That is: A man should not be judged (判断) by the colour of his skin, but by the content of his character," wrote ABC news.
1. Obama was born in ______.
A. Britain
B. America
D. Indonesia
2. There was / were ______ black student(s) besides Obama at the school where he studied when && &he was ten.
3. Obama became the first black president in US history when he was ______.
4. Which of the following is TRUE?
A. Obama's father was a Kenyan prince.
B. Obama once forgot who his father was with the help of alcohol. C. When he was young, Obama was so dishonest that nobody believed in him.
D. Obama changed his college life because of his friends' help and his hard work.
5. From the passage we can see that ______.
A. we could judge a person by the colour of his skin
B. we could not judge a person by the content of his character
C. we should not judge a person by the colour of his skin
D. we should judge a person by what he did when he was young
我有更好的答案
1. B& 2. C&&3.&C &4. D& 5. C
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出门在外也不愁统计题目,求解答过程2011年城镇单位从业人员人数：1月1日：140.2万人,3月1日：142.5,7月1日：144.1；11月1日：149.5；12月31日：148.82011年该市的年平均城镇单位从业人员人数是多少?_百度作业帮
统计题目,求解答过程2011年城镇单位从业人员人数：1月1日：140.2万人,3月1日：142.5,7月1日：144.1；11月1日：149.5；12月31日：148.82011年该市的年平均城镇单位从业人员人数是多少?
统计题目,求解答过程2011年城镇单位从业人员人数：1月1日：140.2万人,3月1日：142.5,7月1日：144.1；11月1日：149.5；12月31日：148.82011年该市的年平均城镇单位从业人员人数是多少?
1-2月天数为59、3-6月天数为122、7-10月天数为123、11-12月天数为61.年平均城镇单位从业人员人数=[½(140.2+142.5)×59+½(142.5+144.1)×122+½(144.1+149.5)×123+½(149.5+148.8)×61]÷365=145.14
加起来，取平均，即可
不对的，加起来取平均数是145.02，但是答案是145.15
时间点都不一样的，不会就是简单平均的