2/15+2/35+2/63+.+2/323=
问题描述:
2/15+2/35+2/63+.+2/323=
答
2/15+2/35+2/63+.+2/323
=1/3-1/5+1/5-1/7+1/7-1/9+.+1/15-1/17+1/17-1/19
=1/3-1/19
=(19-3)/3*19
=16/57