帮帮做 |-1+1/2|+|-1/2+1/3|+|-1/3+1/4|+.+|-1/9+1/10|=___

问题描述:

帮帮做 |-1+1/2|+|-1/2+1/3|+|-1/3+1/4|+.+|-1/9+1/10|=___

|-1+1/2|+|-1/2+1/3|+|-1/3+1/4|+.+|-1/9+1/10|
=(1-1/2)+(1/2-1/3)+(1/3-1/4)+.+(1/9-1/10)
=1-1/10
=9/10