1⼀3+1⼀15+1⼀35+1⼀63+1⼀99+1⼀143=?怎样简便计算?请写过程

2024-11-22 22:16:46
推荐回答(1个)
回答1:

1/3+1/15+1/35+1/63+1/99+1/143
=1/2x(1-1/3)+1/2x(1/3-1/5)+.....1/2x(1/9-1/11)+1/2(1/11-1/13)
=1/2x(1-1/3+1/3-1/5+....+1/9-1/11+1/11-1/13)
=1/2x(1-1/13)
=1/2x12/13
=6/13