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当x>2时,不等式http://picflow.koolearn.com/upload/papers/g02/20111024/201110241518295931015.gif恒成立,则实数a的

发布时间:2021-07-21

A.最小值是8

B.最小值是6

C.最大值是8

D.最大值是6

试卷相关题目

  • 1若函数f(x)=x+http://picflow.koolearn.com/upload/papers/g02/20110824/20110824105928781920.gif(x>2)在x=a处有最小值,则a=

    A.1+http://picflow.koolearn.com/upload/papers/g02/20110824/20110824105928796887.gif

    B.1+http://picflow.koolearn.com/upload/papers/g02/20110824/20110824105928828883.gif

    C.3

    D.4

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  • 2某公司一年购买某种货物400吨,每次都购买x吨,运费为4万元/次,一年的总存储费用为4x万元,要使一年的总运费与总存储费用之和最小,则x的值为

    A.15

    B.20

    C.30

    D.40

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  • 3已知x≥http://picflow.koolearn.com/upload/papers/g02/20110829/20110829114934671878.gif,则f(x)=http://picflow.koolearn.com/upload/papers/g02/20110829/201108291149346711034.gif

    A.最大值http://picflow.koolearn.com/upload/papers/g02/20110829/20110829114934703882.gif

    B.最小值http://picflow.koolearn.com/upload/papers/g02/20110829/20110829114934703882.gif

    C.最大值1

    D.最小值1

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  • 4下列不等式: ①a2+1>2a;②a2+4≥4a;③|http://picflow.koolearn.com/upload/papers/g02/20110829/20110829095909796959.gif|≥2;④http://picflow.koolearn.com/upload/papers/g02/20110829/201108290959097961070.gif。 其中恒成立的是

    A.①④

    B.③④

    C.②③

    D.①②

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  • 5已知http://picflow.koolearn.com/upload/papers/g02/20110923/20110923093236046956.gif=1(x>0,y>0),则x+y的最小值为[      ]

    A.12

    B.14

    C.16

    D.18

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  • 6当x>2时,不等式x+http://picflow.koolearn.com/upload/papers/g02/20111101/20111101130114859929.gif≥a恒成立,则实数a的

    A.最小值是8

    B.最小值是6

    C.最大值是8

    D.最大值是6

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  • 7某商场中秋前30天月饼销售总量f(t)与时间t(0<t≤30)的关系大致满足f(t)=t2+10t+16,则该商场前t天平均售出(如前10天的平均售出为http://picflow.koolearn.com/upload/papers/g02/20111031/20111031100542000932.gif)的月饼最少为

    A.18

    B.27

    C.20

    D.16

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  • 8已知f(x)=http://picflow.koolearn.com/upload/papers/g02/20110827/20110827161356468933.gif,a,b∈R,A=f(http://picflow.koolearn.com/upload/papers/g02/20110827/20110827161356500934.gif),G=f(http://picflow.koolearn.com/upload/papers/g02/20110827/20110827161356500909.gif),H=f(http://picflow.koolearn.com/upload/papers/g02/20110827/20110827161356515966.gif),则

    A.G.H的大小关系是 A.A≤G≤H

    B.A≤H≤G

    C.G≤H≤A

    D.H≤G≤A

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  • 9设x,y满足约束条件http://picflow.koolearn.com/upload/papers/g02/20110919/201109191414255623140.gif,若目标函数z=ax+by(a>0,b>0)最大值为12,则http://picflow.koolearn.com/upload/papers/g02/20110919/20110919141425562936.gif的最小值为

    A.http://picflow.koolearn.com/upload/papers/g02/20110919/20110919141425625887.gif

    B.http://picflow.koolearn.com/upload/papers/g02/20110919/20110919141425656892.gif

    C.5

    D.4

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  • 10下列关于实数x的不等关系中,恒成立的是

    A.|x-1|-|x-2|≤3

    B.x+http://picflow.koolearn.com/upload/papers/g02/20110922/20110922161528937864.gif≥2

    C.http://picflow.koolearn.com/upload/papers/g02/20110922/201109221615289531018.gif

    D.x2+1>2x

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