把1分解开的思路,是逐步分解,层层展开,得其结果如下：
1
=1/2+1/2
=1/2+1/3+1/6
=1/2+1/4+1/12+1/9+1/18
=1/2+1/4+1/12+1/9+1/27+1/54
=1/2+1/4+1/18+1/36+1/9+1/27+1/54
=1/3+1/4+1/6+1/9+1/18+1/27+1/36+1/54