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1、专业好文档工程数学作业（一）答案（满分100分）第2章 矩阵（一）单项选择题（每小题2分，共20分） 设，则（D） A. 4 B. 4 C. 6 D. 6 若，则（A） A. B. 1 C. D. 1 乘积矩阵中元素（C） A. 1 B. 7 C. 10 D. 8 设均为阶可逆矩阵，则下列运算关系正确的是（B） A. B. C. D. 设均为阶方阵，且，则下列等式正确的是（D） A. B. C. D. 下列结论正确的是（A） A. 若是正交矩阵，则也是正交矩阵 B. 若均为阶对称矩阵，则也是对称矩阵 C. 若均为阶非零矩阵，则也是非零矩阵 D. 若均为阶非零矩阵，则 矩阵的伴随矩阵为（C） A
2、. B. C. D. 方阵可逆的充分必要条件是（B） A. B. C. D. 设均为阶可逆矩阵，则（D） A. B. C. D. 设均为阶可逆矩阵，则下列等式成立的是（A） A. B. C. D. （二）填空题（每小题2分，共20分） 7 是关于的一个一次多项式，则该多项式一次项的系数是 2 若为矩阵，为矩阵，切乘积有意义，则为 54 矩阵 二阶矩阵 设，则 设均为3阶矩阵，且，则 72 设均为3阶矩阵，且，则 3 若为正交矩阵，则 0 矩阵的秩为 2 设是两个可逆矩阵，则（三）解答题（每小题8分，共48分） 设，求；答案： 设，求解： 已知，求满足方程中的解： 写出4阶行列式中元素的代数余子
3、式，并求其值答案： 用初等行变换求下列矩阵的逆矩阵： ； ； 解：（1）（2）(过程略) (3) 求矩阵的秩解： （四）证明题（每小题4分，共12分） 对任意方阵，试证是对称矩阵证明： 是对称矩阵 若是阶方阵，且，试证或 证明： 是阶方阵，且或 若是正交矩阵，试证也是正交矩阵证明： 是正交矩阵 即是正交矩阵If we dont do that it will go on and go on. We have to stop it; we need the courage to do it.His comments came hours after Fifa vice-president Jef
4、frey Webb - also in London for the FAs celebrations - said he wanted to meet Ivory Coast international Toure to discuss his complaint.CSKA general director Roman Babaev says the matter has been exaggerated by the Ivorian and the British media.Blatter, 77, said: It has been decided by the Fifa congre
5、ss that it is a nonsense for racism to be dealt with with fines. You can always find money from somebody to pay them.It is a nonsense to have matches played without spectators because it is against the spirit of football and against the visiting team. It is all nonsense.We can do something better to
6、 fight racism and discrimination.This is one of the villains we have today in our game. But it is only with harsh sanctions that racism and discrimination can be washed out of football.The (lack of) air up there Watch mCayman Islands-based Webb, the head of Fifas anti-racism taskforce, is in London
7、for the Football Associations 150th anniversary celebrations and will attend Citys Premier League match at Chelsea on Sunday.I am going to be at the match tomorrow and I have asked to meet Yaya Toure, he told BBC Sport.For me its about how he felt and I would like to speak to him first to find out w
8、hat his experience was.Uefa hasopened disciplinary proceedings against CSKAfor the racist behaviour of their fans duringCitys 2-1 win.Michel Platini, president of European footballs governing body, has also ordered an immediate investigation into the referees actions.CSKA said they were surprised an
9、d disappointed by Toures complaint. In a statement the Russian side added: We found no racist insults from fans of CSKA.Baumgartner the disappointing news: Mission aborted.The supersonic descent could happen as early as Sunda.The weather plays an important role in this mission. Starting at the groun
10、d, conditions have to be very calm - winds less than 2 mph, with no precipitation or humidity and limited cloud cover. The balloon, with capsule attached, will move through the lower level of the atmosphere (the troposphere) where our day-to-day weather lives. It will climb higher than the tip of Mo
11、unt Everest (5.5 miles/8.85 kilometers), drifting even higher than the cruising altitude of commercial airliners (5.6 miles/9.17 kilometers) and into the stratosphere. As he crosses the boundary layer (called the tropopause),e can expect a lot of turbulence.The balloon will slowly drift to the edge
12、of space at 120,000 feet ( Then, I would assume, he will slowly step out onto something resembling an Olympic diving platform.Below, the Earth becomes the concrete bottom of a swimming pool that he wants to land on, but not too hard. Still, hell be traveling fast, so despite the distance, it will no
13、t be like diving into the deep end of a pool. It will be like he is diving into the shallow end.Skydiver preps for the big jumpWhen he jumps, he is expected to reach the speed of sound - 690 mph (1,110 kph) - in less than 40 seconds. Like hitting the top of the water, he will begin to slow as he app
14、roaches the more dense air closer to Earth. But this will not be enough to stop him completely.If he goes too fast or spins out of control, he has a stabilization parachute that can be deployed to slow him down. His team hopes its not needed. Instead, he plans to deploy his 270-square-foot (25-square-meter) main chute at an altitude of around 5,000 feet (1,524 meters).In order to deploy this chute successfully, he will have to sl
