问题 选择题 数列{an}的通项为an=nn+2,则有( )A.an>an-1B.an<an-1C.an=an-1D.不能确定 答案 an=nn+2=1-2n+2,∵2n+2递减,∴-2n+2递增,∴an=1-2n+2递增,∴an>an-1,故选A.