已知数列AN的前N项和SN,SN=2N^2+3n+2,求an_数学解答

已知数列AN的前N项和SN,SN=2N^2+3n+2,求an

人气：339 ℃　时间：2019-10-19 05:47:10

解答

A(n+1)
=S(n+1)-Sn
=2(n+1)^2+3(n+1)+2-2n^2-3n-2
=2n^2+4n+2+3n+3-2n^2-3n
=4n+5
An=5+4(n-1)