已知等比数列{an}为递增数列,且a52=a10,2(an+an+2)=5an+1,则数列{an}的通项公式为_.

问题描述:

已知等比数列{an}为递增数列,且a52a10,2(an+an+2)=5an+1,则数列{an}的通项公式为______.

设数列的公比为q,首项为a1,则
a52a10,2(an+an+2)=5an+1
∴(a1q42=a1q9,2(1+q2)=5q,
∵等比数列{an}为递增数列,
∴q=2,a1=2
an2n
故答案为:an2n