正项等比数列{a
n}的前n项和记为S
n,a
1=1,S
3=13
(Ⅰ)求{a
n}的通项公式;
(Ⅱ)等差数列{b
n}的各项为正,且b
2=5,又a
1+b
1,a
2+b
2,a
3+b
3成等比数列,设A
n=a
nb
n,求{A
n}的前n项和T
n.
考点分析:
相关试题推荐
![manfen5.com 满分网](http://img.manfen5.com/res/GZSX/web/STSource/20131101225233649608539/SYS201311012252336496085018_ST/images0.png)
如图,已知三棱锥A-BPC中,AP⊥PC,AC⊥BC,M为AB中点,D为PB中点,且△PMB为正三角形.
(1)求证:DM∥平面APC;
(2)求证:平面ABC⊥平面APC;
(3)若BC=4,AB=20,求三棱锥D-BCM的体积.
查看答案
设f(x)是定义在[2m,2-m]上的奇函数,且对任意a,b∈[2m,2-m],a-b≠0时,都有
![manfen5.com 满分网](http://img.manfen5.com/res/GZSX/web/STSource/20131101225233649608539/SYS201311012252336496085017_ST/0.png)
.
(Ⅰ)求实数m的值;
(Ⅱ)解不等式f(2x-3)>f(x+1).
查看答案
已知向量
![manfen5.com 满分网](http://img.manfen5.com/res/GZSX/web/STSource/20131101225233649608539/SYS201311012252336496085016_ST/0.png)
.
(1)当
![manfen5.com 满分网](http://img.manfen5.com/res/GZSX/web/STSource/20131101225233649608539/SYS201311012252336496085016_ST/1.png)
时,求
![manfen5.com 满分网](http://img.manfen5.com/res/GZSX/web/STSource/20131101225233649608539/SYS201311012252336496085016_ST/2.png)
的值;
(2)求f(x)=(
![manfen5.com 满分网](http://img.manfen5.com/res/GZSX/web/STSource/20131101225233649608539/SYS201311012252336496085016_ST/3.png)
+
![manfen5.com 满分网](http://img.manfen5.com/res/GZSX/web/STSource/20131101225233649608539/SYS201311012252336496085016_ST/4.png)
)•
![manfen5.com 满分网](http://img.manfen5.com/res/GZSX/web/STSource/20131101225233649608539/SYS201311012252336496085016_ST/5.png)
在
![manfen5.com 满分网](http://img.manfen5.com/res/GZSX/web/STSource/20131101225233649608539/SYS201311012252336496085016_ST/6.png)
上的值域.
查看答案
有以下四个命题:
①若命题p:∀x∈R,x>sinx,则¬p:∃x∈R,x<sinx
②函数y=sin(x-
![manfen5.com 满分网](http://img.manfen5.com/res/GZSX/web/STSource/20131101225233649608539/SYS201311012252336496085015_ST/0.png)
]在R上是奇函数.
③把函数y=3sin(2x+
![manfen5.com 满分网](http://img.manfen5.com/res/GZSX/web/STSource/20131101225233649608539/SYS201311012252336496085015_ST/1.png)
向左平移
![manfen5.com 满分网](http://img.manfen5.com/res/GZSX/web/STSource/20131101225233649608539/SYS201311012252336496085015_ST/2.png)
得到y=3sin2x的图象.
④若函数f(x)=-cos
2x+
![manfen5.com 满分网](http://img.manfen5.com/res/GZSX/web/STSource/20131101225233649608539/SYS201311012252336496085015_ST/3.png)
(x∈R),则f(x)是最小正周期为φ=
![manfen5.com 满分网](http://img.manfen5.com/res/GZSX/web/STSource/20131101225233649608539/SYS201311012252336496085015_ST/4.png)
的偶函数
⑤设圆x
2+y
2-4x-2y-8=0上有关于直线ax+2by-2=0(a,b>0)对称的两点,则
![manfen5.com 满分网](http://img.manfen5.com/res/GZSX/web/STSource/20131101225233649608539/SYS201311012252336496085015_ST/5.png)
的最小值为3+2
![manfen5.com 满分网](http://img.manfen5.com/res/GZSX/web/STSource/20131101225233649608539/SYS201311012252336496085015_ST/6.png)
其中正确命题的序号是
(把你认为正确命题的序号都填上).
查看答案
已知函数y=f (x),x∈[0,2π]的导函数y=f'(x)的图象,如图所示,则y=f (x) 的单调增区间为
.
查看答案