f(n)=1+3n(n-1) 证明1/(f1)+1/(f2)+1/(f3)+……+1/(fn)扫码下载作业帮拍照答疑一拍即得
问题描述:
f(n)=1+3n(n-1) 证明1/(f1)+1/(f2)+1/(f3)+……+1/(fn)
扫码下载作业帮
拍照答疑一拍即得
答
f(1)=1
n>=2时,1/ f(n) = 1/3* [1/(n-1) - 1/n] }
1/(f1)+1/(f2)+1/(f3)+……+1/(fn)