1/1X2 +1/2X3+1/3X4+……1/10X11

问题描述:

1/1X2 +1/2X3+1/3X4+……1/10X11

1/1X2 +1/2X3+1/3X4+……1/10X11
=(1/1-1/2)+(1/2-1/3)+……+(1/10-1/11)
=1/1-1/11
=10/11