Sn=2an+(-1)n次方 怎么求an
问题描述：
Sn=2an+(-1)n次方 怎么求an
答
n=1时,a1=S1=2a1+(-1)a1=1n≥2时,an=Sn-S(n-1)=2an+(-1)ⁿ-[2a(n-1)+(-1)^(n-1)]an=2a(n-1)-2×(-1)ⁿan+(2/3)×(-1)ⁿ=2a(n-1)+(4/3)×(-1)^(n-1)[an+(2/3)×(-1)ⁿ]/[a(n-1)+(2/3)×(-1)^(n-1...