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给出下列四个命题: ①已知a,b,m都是正数,且,则a<b; ②若函数f(x)=...
给出下列四个命题:
①已知a,b,m都是正数,且
![manfen5.com 满分网](http://img.manfen5.com/res/GZSX/web/STSource/20131101231426650268958/SYS201311012314266502689014_ST/0.png)
,则a<b;
②若函数f(x)=lg(ax+1)的定义域是{x|x<1},则a<-1;
③已知x∈(0,π),则y=sinx+
![manfen5.com 满分网](http://img.manfen5.com/res/GZSX/web/STSource/20131101231426650268958/SYS201311012314266502689014_ST/1.png)
的最小值为
![manfen5.com 满分网](http://img.manfen5.com/res/GZSX/web/STSource/20131101231426650268958/SYS201311012314266502689014_ST/2.png)
;
④已知a、b、c成等比数列,a、x、b成等差数列,b、y、c也成等差数列,则
![manfen5.com 满分网](http://img.manfen5.com/res/GZSX/web/STSource/20131101231426650268958/SYS201311012314266502689014_ST/3.png)
的值等于2.其中正确命题的序号是
.
考点分析:
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