已知数列an满足an-1=an=2n-3(n∈N*)且a1=2,求an谢谢抓紧时间啊,这是高一学的求通向公式an啊打错了是an-1=an+2n-3

Question

已知数列an满足an-1=an=2n-3(n∈N*)且a1=2,求an
谢谢抓紧时间啊,这是高一学的
求通向公式an啊 打错了是an-1=an+2n-3

Answer 1

a1=a2+2*2-3a2=a3+2*3-3……an-1=an+2*n-3累加得：a1+a2+……+an-1=a1+a2+……+an-1+an-a1+2*(2+3+……+n)-3*(n-1)等式同时减去a1+a2+……+an-1得an=a1+3*(n-1)-2*(2+3+……+n)整理的an=-n^2+2*n+1...