1+2/1-6/5+12/7-20/9+30/11-42/13+56/15-72/17=?

问题描述:

1+2/1-6/5+12/7-20/9+30/11-42/13+56/15-72/17=?
,这是/分数线

1+2/1-6/5+12/7-20/9+30/11-42/13+56/15-72/17
=1+2/1-2/1-3/1+3/1+4/1-4/1-5/1+5/1+6/1-6/1-7/1+7/1+8/1-8/1-9/1
=1-9/1
=9/8