Question

f(n)=1+1/2+1/3+....+1/(3n-1) (n∈N*) 那么f(n+1)-f(n)=

RT 需要详细过程 本人仅仅是高二生

Answer 1

f(n)=1+1/2+1/3+....+1/(3n-1)
f(n+1)=1+1/2+1/3+....+1/(3n-1)+1/(3(n+1)-1)
f(n+1)-f(n)=1/(3(n+1)-1) =1/(3n+2)

Answer 2

1/3n+1/(3n+1)+1/(3n+2)

Answer 3

1/3n+1/(3n+1)+1/(3n+2)

Answer 4

1／（3N－1）