满分5 >
高中数学试题 >
设x、y满足约束条件,若目标函数z=ax+by(其中a>0,b>0)的最大值为3...
设x、y满足约束条件
![manfen5.com 满分网](http://img.manfen5.com/res/GZSX/web/STSource/20131025124017969508211/SYS201310251240179695082007_ST/0.png)
,若目标函数z=ax+by(其中a>0,b>0)的最大值为3,则
![manfen5.com 满分网](http://img.manfen5.com/res/GZSX/web/STSource/20131025124017969508211/SYS201310251240179695082007_ST/1.png)
的最小值为( )
A.4
B.3
C.2
D.1
考点分析:
相关试题推荐
函数
![manfen5.com 满分网](http://img.manfen5.com/res/GZSX/web/STSource/20131025124017969508211/SYS201310251240179695082006_ST/0.png)
的图象向右平移a个单位后所得的图象关于点
![manfen5.com 满分网](http://img.manfen5.com/res/GZSX/web/STSource/20131025124017969508211/SYS201310251240179695082006_ST/1.png)
中心对称.则a不可能是( )
A.
![manfen5.com 满分网](http://img.manfen5.com/res/GZSX/web/STSource/20131025124017969508211/SYS201310251240179695082006_ST/2.png)
B.
![manfen5.com 满分网](http://img.manfen5.com/res/GZSX/web/STSource/20131025124017969508211/SYS201310251240179695082006_ST/3.png)
C.
![manfen5.com 满分网](http://img.manfen5.com/res/GZSX/web/STSource/20131025124017969508211/SYS201310251240179695082006_ST/4.png)
D.
查看答案
已知函数y=f (x)在R上是偶函数,对任意x∈R都有f(x+6)=f(x)+f(3),当x
1,x
2∈[0,3]且x
1≠x
2时,
![manfen5.com 满分网](http://img.manfen5.com/res/GZSX/web/STSource/20131025124017969508211/SYS201310251240179695082005_ST/0.png)
,给出如下命题:f(2a-x)=f(x)
①f(3)=0
②直线x=-6是y=f(x)图象的一条对称轴
③函数y=f(x)在[-9,-6]上为增函数
④函数y=f(x)在[-9,9]上有四个零点.
其中所有正确命题的序号为( )
A.①②
B.②④
C.①②③
D.①②④
查看答案
下列四个命题中,真命题的个数为( )
①若函数f(x)=sinx-cosx+1,则y=|f(x)|的周期为2π;
②若函数f(x)=cos
4x-sin
4,则
![manfen5.com 满分网](http://img.manfen5.com/res/GZSX/web/STSource/20131025124017969508211/SYS201310251240179695082004_ST/0.png)
=-1;
③若角α的终边上一点P的坐标为(sin
![manfen5.com 满分网](http://img.manfen5.com/res/GZSX/web/STSource/20131025124017969508211/SYS201310251240179695082004_ST/1.png)
,cos
![manfen5.com 满分网](http://img.manfen5.com/res/GZSX/web/STSource/20131025124017969508211/SYS201310251240179695082004_ST/2.png)
),则角α的最小正值为
![manfen5.com 满分网](http://img.manfen5.com/res/GZSX/web/STSource/20131025124017969508211/SYS201310251240179695082004_ST/3.png)
;
④函数y=2cos2x的图象可由函数y=cos2x+
![manfen5.com 满分网](http://img.manfen5.com/res/GZSX/web/STSource/20131025124017969508211/SYS201310251240179695082004_ST/4.png)
sin2x的图象向左平移m=-1个单位得到.
A.1
B.2
C.3
D.4
查看答案
已知数列{a
n}为等差数列,{b
n}为等比数列,且满足:a
1000+a
1012=π,b
1b
14=-2,则
![manfen5.com 满分网](http://img.manfen5.com/res/GZSX/web/STSource/20131025124017969508211/SYS201310251240179695082003_ST/0.png)
=( )
A.1
B.-1
C.
![manfen5.com 满分网](http://img.manfen5.com/res/GZSX/web/STSource/20131025124017969508211/SYS201310251240179695082003_ST/1.png)
D.
查看答案
若方程lnx+x-4=0在区间(a,b)(a,b∈Z,且b-a=1)上有一根,则a的值为( )
A.1
B.2
C.3
D.4
查看答案