证明:1/f(1)+1/f(2)+1/f(3)+...+1/f(n)
问题描述:
证明:1/f(1)+1/f(2)+1/f(3)+...+1/f(n)f(n)=n^3-(n-1)^3
答
1/ ((n+1)^3-n^3)= 1/(3n^2+3n+1) 1/f(1)+1/f(2)+1/f(3)+...+1/f(n)
证明:1/f(1)+1/f(2)+1/f(3)+...+1/f(n)f(n)=n^3-(n-1)^3
1/ ((n+1)^3-n^3)= 1/(3n^2+3n+1) 1/f(1)+1/f(2)+1/f(3)+...+1/f(n)