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(时间:60分钟,满分:80分)
一、选择题(共6小题,每小题5分,满分30分)
1.(2012广东六校第二次联考)已知函数y=xln x,则这个函数在点x=1处的切线方程是
( )
A.y=2x-2 B.y=2x+2
C.y=x-1 D.y=x+1
解析:当x=1时,y=0;y′=ln x+1,k=y′|x=1=1,所以切线方程为y=x-1,故选C.
答案:C
2.已知f(x)=x2+2xf′(1)则f′(0)等于( )
A.0 B.-4
C.-2 D.2
解析:f′(x)=2x+2f′(1),
∴f′(1)=2+2f′(1)即f′(1)=-2,
∴f′(x)=2x-4,∴f′(0)=-4.
答案:B
3.(2011湖南高考)曲线y=-在点M处的切线的斜率为( )
A.- B.
C.- D.
解析:y′==,把x=代入得导数值为.
答案:B
4.(2012年河南十校联考)在函数y=x3-9x的图象上,满足在该点处的切线的倾斜角小于,
且横、纵坐标都为整数的点的个数是( )
A.0 B.1
C.2 D.3
解析:依题意得,y′=3x2-9,令0<y′<1得3<x2<,显然满足该不等式的整数x不存在,因此在函数y=x3-9x的图象上,满足在该点处的切线的倾斜角小于,且横、纵坐标都为整数的点的个数是0,选A.
答案:A
5.设函数y=xsin x+cos x的图像上的点(x,y)处的切线斜率为k,若k=g(x),则函数k=
g(x)的图像大致为( )
解析:k=g(x)=y′=sin x+xcos x-sin x=xcos x,
故函数k=g(x)为奇函数,排除A、C;
又当x∈时,g(x)>0.
答案:B
6.f(x)与g(x)是定义在R上的两个可导函数,若f(x),g(x)满足f′(x)=g′(x),则f(x)与
g(x)满足( )
A.f(x)=g(x)
B.f(x)=g(x)=0
C.f(x)-g(x)为常数函数
D.f(x)+g(x)为常数函数
解析:由f′(x)=g′(x),得f′(x)-g′(x)=0,
即[f(x)-g(x)]′=0,
所以f(x)-g(x)=C(C为常数).
答案:C
二、填空题(共3小题,每小题5分,共15分)
7.(2012年青岛质检)如图所示,函数y=f(x)的图像在点P处的切线方程
是y=-2x+9,则f(4)+f′(4)的值为________.
解析:因为f(4)=-2×4+9=1,f′(4)=-2,
所以f(4)+f′(4)=1+(-2)=-1.
答案:-1
8.(2012年全国原创模拟)已知直线y=x+1与曲线y=ln(x+a)相切,则a的值为________.
解析:本题主要考查导数的几何意义.函数y=ln(x+a)的导数为y′=,设切点(x0, y0),则切线方程y-ln(x0+a)=(x-x0),即y=x+1,所以
解得a=2.
答案:2
9.设P为曲线C:y=x2-x+1上一点,曲线C在点P处的切线的斜率的范围是[-1,3],
则点P纵坐标的取值范围是________.
解析:设P(a,a2-a+1),
y′|x=a=2a-1∈[-1,3],∴0≤a≤2.
而g(a)=a2-a+1=2+,
当a=时,g(a)min=.
a=2时,g(a)max=3,故P点纵坐标范围是.
答案:
三、解答题(共3小题,满分35分)
10.已知函数f(x)=2x3+ax与g(x)=bx2+c的图像都过点P(2,0),且在点P处有公共切线,
求f(x)、g(x)的表达式.
解析:∵f(x)=2x3+ax图像过点P(2,0),
∴a=-8,∴f(x)=2x3-8x,
∴f′(x)=6x2-8.
对于g(x)=bx2+c,图像过点P(2,0),则4b+c=0.
又g′(x)=2bx,g′(2)=4b=f′(2)=16,
∴b=4,∴c=-16,
∴g(x)=4x2-16.
综上可知,f(x)=2x3-8x,g(x)=4x2-16.
11.求下列函数的导数.
(1)y=x2sin x;(2)y=;
解析:(1)y′=(x2)′sin x+x2(sin x)′
=2xsin x+x2cos x.
(2)法一:y′=
==.
法二:∵y==1+,
∴y′=1′+′,即y′=.
12.设曲线C:y=-ln x(0<x≤1)在点M(e-t,t)(t≥0)处的切线为l.
(1)求直线l的方程;
(2)若直线l与x轴、y轴所围成的三角形面积为S(t),求S(t)的最大值.
解析:(1)因为y′=(-ln x)′=-(0<x≤1),
所以在点M(e-t,t)处的切线l的斜率为-et,
故切线l的方程为y-t=-et(x-e-t),
即etx+y-1-t=0.
(2)令x=0,得y=t+1;令y=0,得x=.
所以S(t)=(t+1)=(t+1)2e-t(t≥0),
从而S′(t)=e-t(1-t)(1+t).
因为当t∈[0,1),S′(t)>0;当t∈(1,+∞)时,S′(t)<0,
所以S(t)的最大值为S(1)=.
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以下是大学体验英语综合教程2(第三版)课后翻译答案
Unit1
1. 任何年满18岁的人都有资格投票。(be eligible to, vote)
Answer:Anyone over the age of 18 is eligible to vote.
2. 每学期开学前,这些奖学金的申请表格就会由学校发给每一个学生。(apply for, scholarship)
Answer:A form to apply for these scholarships is sent by the university to every student before the start of every semester.
3. 遵照医生的建议,我决定戒烟。(on the advice of)
Answer:On the advice of my doctor, I decided to give up smoking.
4. 公园位于县城的正中央。(be located in)
Answer:The park is located right in the center of town.
5. 这所大学提供了我们所需的所有材料和设备。(facilities)
Answer:The university provides all the materials and facilities we desire.
1. 他们花了多年的时间寻找内心的平静,但是收效甚微。(search for)
Answer:They spent many years searching for peace of mind, but with little success.
2. 这种新药的成功研制已经使许多疾病的治疗发生了根本性的变革。(revolutionize)
Answer:The successful development of the new drug has revolutionized the treatment of many diseases.
3. 由于这个国家的经济不景气,这家公司濒于破产。(on the edge of)
Answer:The company is on the edge of bankruptcy due to the economic depression in the country.
4. 大学毕业后他成为了一名护士。他认为护士这一职业可能很有发展前途。(rewarding)
Answer:He became a nurse after college. He thought nursing could be a very rewarding career.
5. 他像往常一样在文件上签了名。(just as)
Answer:He signed his name on the paper just as he has always done it.
Unit2
1. 警察们正忙着填写关于这场事故的各种表格。(fill out)
Answer:The policemen are busy fi lling out forms about the accident.
2. 我想在还车之前把油箱加满。(fill up, fuel tank)
Answer:I want to fi ll up the fuel tank before returning the car.
3. 如果你要投诉,最好遵循正确的程序。(follow the procedure)
Answer:If you want to make a complaint, you’d better follow the correct procedure.
4. 要不是约翰帮忙,我们绝不会这么快就完成实验。(without)
Answer:We couldn’t have fi nished the experiment so soon without John’s help.
5. 暴风雨之后,岸边的人们焦急地搜索湖面以期发现小船的踪迹。(scan for)
Answer:After the storm, the people on the shore anxiously scanned the lake for any sign of the boat.
1. 这个国家不大,但是在国际事务中它却发挥着重要作用。(play a role)
Answer:This country is not big, but it plays an important role in international affairs.
2. 正是在我叔叔的帮助下,我得以克服困难,按时完成了任务。(it is ... that)
Answer:It was with the help of my uncle that I overcame the difficulty and completed the assignment in time.
3. 毕业时他决定留在北京,而他最好的朋友却选择了去西藏。(while)
Answer:While he decided to stay in Beijing upon graduation, his best friend chose to go to Tibet.
4. 在这次校园英语演讲比赛中,我们班的玛丽获得了第三名。(come in)
Answer:In this Campus English Speaking Contest, Mary from our class came in third.
5. 你应该知道学习弹钢琴需要有时间,有金钱,还要有毅力。(as well as)
Answer:You should know that it takes time, money as well as perseverance to learn to play the piano.
Unit3
1.
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