電大土木工程工程數學形成性考核冊答案

1、專業(yè)好文檔工程數學作業(yè)（一）答案（滿分100分）第2章 矩陣（一）單項選擇題（每小題2分，共20分） 設，則（d） a. 4 b. 4 c. 6 d. 6 若，則（a） a. b. 1 c. d. 1 乘積矩陣中元素（c） a. 1 b. 7 c. 10 d. 8 設均為階可逆矩陣，則下列運算關系正確的是（b） a. b. c. d. 設均為階方陣，且，則下列等式正確的是（d） a. b. c. d. 下列結論正確的是（a） a. 若是正交矩陣，則也是正交矩陣 b. 若均為階對稱矩陣，則也是對稱矩陣 c. 若均為階非零矩陣，則也是非零矩陣 d. 若均為階非零矩陣，則 矩陣的伴隨矩陣為（c） a

2、. b. c. d. 方陣可逆的充分必要條件是（b） a. b. c. d. 設均為階可逆矩陣，則（d） a. b. c. d. 設均為階可逆矩陣，則下列等式成立的是（a） a. b. c. d. （二）填空題（每小題2分，共20分） 7 是關于的一個一次多項式，則該多項式一次項的系數是 2 若為矩陣，為矩陣，切乘積有意義，則為 54 矩陣 二階矩陣 設，則 設均為3階矩陣，且，則 72 設均為3階矩陣，且，則 3 若為正交矩陣，則 0 矩陣的秩為 2 設是兩個可逆矩陣，則（三）解答題（每小題8分，共48分） 設，求；答案： 設，求解： 已知，求滿足方程中的解： 寫出4階行列式中元素的代數余子

3、式，并求其值答案： 用初等行變換求下列矩陣的逆矩陣： ； ； 解：（1）（2）(過程略) (3) 求矩陣的秩解： （四）證明題（每小題4分，共12分） 對任意方陣，試證是對稱矩陣證明： 是對稱矩陣 若是階方陣，且，試證或 證明： 是階方陣，且或 若是正交矩陣，試證也是正交矩陣證明： 是正交矩陣 即是正交矩陣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 slow to 172 mph (277 kph). he will have a reserve parachute that will open automatically if he loses consciousness a