关于绝对值|1/21-1/20|+|1/22-1/21|+|1/23-1/22|+...|1/30-1/29|
问题描述:
关于绝对值|1/21-1/20|+|1/22-1/21|+|1/23-1/22|+...|1/30-1/29|
答
=1/20-1/21+1/21-1/22+...+1/29-1/29+1/29-1/30
=1/20+(-1/21+1/21)+(-1/22+1/22)+.+(-1/29+1/29)-1/30
=1/20-1/30
=1/60