1/1x2+1/2x3+1/3x4+1/4x5+……1/8x9+1/9x10=?(简便算法)
问题描述:
1/1x2+1/2x3+1/3x4+1/4x5+……1/8x9+1/9x10=?(简便算法)
快~~~~~
答
1/1x2+1/2x3+1/3x4+1/4x5+……1/8x9+1/9x10
=1-1/2+1/2-1/3+1/3-1/4+.+1/8-1/9+1/9-1/10
=1-1/10
=9/10