电大高数试题答案小抄参考

1、专业好文档试题答案一、 单项选择题1. a 2a 3. d 4. d 5. b 6. c 7. b 8. a 9. c 10. b 11. d 12. c二、填空题1. 2. -cos2x + c (c 是任意常数) 3. 4. 5. 0 6. 0 7. 收敛的 8. 2 + 9. 2 10. 三、计算题 解 = = 2解=3解 = xcos(1-x) - = xcos(1-x) + sin(1-x) + c 4解= = 5解 = = 6解 = = =12 7解 = 8解 =-=9解法一 = =1 解法二 令，则 = 10解 因为 ， 用公式 由 ， 得 所以，特解为 11解 将原方程分离变量

2、 两端积分得 lnlny = lnc sinx 通解为 y = ec sinx 12解：移项，分离变量，得 两边求积分，得 通解为： 由，得，c = 1 所以，满足初始条件的特解为： 13解 将方程分离变量： 等式两端积分得 将初始条件代入，得 ，c = 所以，特解为： 14. 解 将原方程化为：，它是一阶线性微分方程， ，用公式 15解 在微分方程中，由通解公式 = = 16解：因为，由通解公式得 = = 四、应用题1解 当产量由4百台增至6百台时，总成本的增量为 = 10 （万元） 又 = = 令 ， 解得. x = 6是惟一的驻点，而该问题确实存在使平均成本达到最小的值. 所以产量为6百

3、台时可使平均成本达到最小. 2解 因为边际利润 =12-0.02x 2 = 10-0.02x 令= 0，得x = 500 x = 500是惟一驻点，而该问题确实存在最大值. 所以，当产量为500件时，利润最大. 当产量由500件增加至550件时，利润改变量为 =500 - 525 = - 25 （元）即利润将减少25元. 3. 解 (x) =(x) -(x) = (100 2x) 8x =100 10x 令(x)=0, 得 x = 10（百台）又x = 10是l(x)的唯一驻点，该问题确实存在最大值，故x = 10是l(x)的最大值点，即当产量为10（百台）时，利润最大. 又 即从利润最大时的

4、产量再生产2百台，利润将减少20万元. 4解：因为总成本函数为 = 当x = 0时，c(0) = 18，得 c =18即 c(x)= 又平均成本函数为 令 ， 解得x = 3 (百台)该题确实存在使平均成本最低的产量. 所以当x = 3时，平均成本最低. 最底平均成本为 (万元/百台) 5解：(1) 因为边际成本为 ，边际利润 = 14 2x 令，得x = 7 由该题实际意义可知，x = 7为利润函数l(x)的极大值点，也是最大值点. 因此，当产量为7百吨时利润最大. (2) 当产量由7百吨增加至8百吨时，利润改变量为 =112 64 98 + 49 = - 1 （万元）即利润将减少1万元.

5、winger tuivasa-sheck, who scored two tries in the kiwis 20-18 semi-final win over england, has been passed fit after a lower-leg injury, while slater has been named at full-back but is still recovering from a knee injury aggravated against usa.both sides boast 100% records heading into the encounter

6、 but australia have not conceded a try since josh charnleys effort in their first pool match against england on the opening day.aussie winger jarryd hayne is the competitions top try scorer with nine, closely followed by tuivasa-sheck with eight.but it is recently named rugby league international fe

7、deration player of the year sonny bill williams who has attracted the most interest in the tournament so far.the kiwi - with a tournament high 17 offloads - has the chance of becoming the first player to win the world cup in both rugby league and rugby union after triumphing with the all blacks in 2

8、011.id give every award back in a heartbeat just to get across the line this weekend, said williams.the (lack of) air up there watch mcayman islands-based webb, the head of fifas anti-racism taskforce, is in london for the football associations 150th anniversary celebrations and will attend citys pr

9、emier 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 what his experience was.uefa hasopened disciplinary proceedings against cskafor the ra

10、cist 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 and disappointed by toures complaint. in a statement the russian side added: we found n

11、o 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 ground, conditions have to be very calm - winds less than 2 mph, with no precipitation or

12、 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 mount everest (5.5 miles/8.85 kilometers), drifting even higher than the cruising alti

13、tude 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 of space at 120,000 feet ( then, i would assume, he will slowly step out onto someth

14、ing resembling an olympic diving platform.they blew it in 2008 when they got caught cold in the final and they will not make the same mistake against the kiwis in manchester.five years ago they cruised through to the final and so far history has repeated itself here - the last try they conceded was

15、scored by englands josh charnley in the opening game of the tournament.that could be classed as a weakness, a team under-cooked - but i have been impressed by the kangaroos focus in their games since then.they have been concentrating on the sort of stuff that wins you tough, even contests - strong d

16、efence, especially on their own goal-line, completing sets and a good kick-chase. theyve been great at all the unglamorous stuff that often goes unnoticed in the stands but not by your team-mates.it is as though their entire tournament has been preparation for the final.in johnathan thurston, cooper cronk, cameron smith and either billy slater or greg inglis at full-back they have a spine that is unmatched in rugby league. they have played in so many high-pressure games - a priceless asset going into saturday.the