问题
填空题
设数列{an}满足a1=1,an+1=3an,则a5=______.
答案
由数列{an}满足a1=1,an+1=3an,可知数列{an}是以1为首项,3为公比的等比数列,
∴a5=1×34=81.
故答案为81.
设数列{an}满足a1=1,an+1=3an,则a5=______.
由数列{an}满足a1=1,an+1=3an,可知数列{an}是以1为首项,3为公比的等比数列,
∴a5=1×34=81.
故答案为81.