|1+1/2|+|1/2+1/3|……+|1/49-1/50|

问题描述:

|1+1/2|+|1/2+1/3|……+|1/49-1/50|

怎么有加有减的?

|1-1/2|+|1/2-1/3|……+|1/49-1/50|
=1-1/2+1/2-1/3……+1/49-1/50
=1-1/50
=49/50