1/2×3+1/3×4+1/5×4……1/98×99+1/99×100=?

=98+1/2+1/3+···+1/99
=97+1+1/2+1/3+···+1/99
=97+ln(99)看不懂。。我才六年级这样啊！那你等等我看错题目了1/2×3+1/3×4+1/5×4……1/98×99+1/99×100
=1/2-1/3+1/3-1/4···+1/99-1/100
=1/2-1/100=49/100能看懂了不？
就是把 1/n*(n-1)分解成1/(n-1)-14n