∑(∞,n=1)(n^2-2n+3)/(n^4+n^2-6)
问题描述：
∑(∞,n=1)(n^2-2n+3)/(n^4+n^2-6)
答
a1=S1=1-2+3=2Sn=n²-2n+3Sn-1=(n-1)²-2(n-1)+3an=Sn-Sn-1=n²-2n+3-(n-1)²+2(n-1)-3=2n-3n=1时,2-3=-1,与a1=2矛盾,因此n=1时,a1=2n≥2时,an=2n-3数列通项公式为an=2 n=12n-3 n≥2...