已知f(n)=3n^2-3n+1求证1/f(1)+1/f(2)+1/f(3)+……1/f(n)<4/3
问题描述:
已知f(n)=3n^2-3n+1求证1/f(1)+1/f(2)+1/f(3)+……1/f(n)<4/3
答
f(n)=3n^2-3n+1;
f(n)=3n(n-1)+1>3n(n-1);
1/f(n)1/f(1)=1;
1/f(2).
1/f(n)1/f(1)+1/f(2)+1/f(3)+……1/f(n)