1⼀20+1⼀30+1⼀42+...+1⼀132+1⼀156简便方法怎么算?

2025-02-24 05:44:47
推荐回答(1个)
回答1:

1/20+1/30+1/42+...+1/132+1/156
=1/4-1/5+1/5-1/6+……+1/12-1/13
=1/4-1/13
=13/52-4/52
=9/52