简算：3/1+15/1+35/1+63/1+99/

简算：3/1+15/1+35/1+63/1+99/1+143/1+195/1=?

1个回答

1/3+1/15+1/35+1/63+1/99+1/143+1/195+1/255+1/323
=1/2(1-1/3+1/3-1/5+1/5-1/7+1/7-1/9+1/9-1/11+1/11-1/13+1/13-1/15+1/15-1/17+1/17-1/19)
=1/2(1-1/19)
=1/2*18/19
=9/19