1/1×2+1/2×3+1/3×4+1/4×5……1/2009×2010等于?

问题描述:

1/1×2+1/2×3+1/3×4+1/4×5……1/2009×2010等于?

=1-1/2+1/2-1/3+1/3-1/4+1/4-1/5+.+1/2009-1/2010
=1-1/2010
=2009/2010
PS:你发错区了.