若数列{an}的项满足（an-an-1-3)(an+an-1)=0,a1=2,则（a2005)max,(a2005)minn-1是下标答案是6014，

Question

若数列{an}的项满足（an-an-1-3)(an+an-1)=0,a1=2,则（a2005)max,(a2005)min
n-1是下标
答案是6014，

Answer 1

（an-an-1-3)(an+an-1)=0,要么：an+an-1=0,即an是以-1为公比的等比数列,a2005=2要么an-an-1-3=0,即an是以3为公差的等差数列,a2005=6014第一种情况给了我们提示,就是可能（a2005-a2004-3)(a2005+a2004)=0是以a2005+a2...