已知数列{an}满足a1=2,an+1-an+1=0(n∈N+),则此数列的通项an等于( ) A.n2+1 B.n+1 C.1-n D.3-n
问题描述:
已知数列{an}满足a1=2,an+1-an+1=0(n∈N+),则此数列的通项an等于( )
A. n2+1
B. n+1
C. 1-n
D. 3-n
答
由题意可得,an+1 -an =-1,此等差数列是以2为首项,以-1为公差的等差数列,
则此数列的通项an =2+(n-1)d=3-n,
故选D.