计算1/1x3+1/2x4+1/3x5+……+1/9x11=?
问题描述:
计算1/1x3+1/2x4+1/3x5+……+1/9x11=?
答
=(1-1|3+1|3-1|5+-------+1|9-1|11)|2
=5|11
答
27.9912698412698
是不是
答
1/1x3+1/2x4+1/3x5+……+1/9x11
=1/2(1-1/3+1/2-1/3+1/3-1/5+...+1/7-1/9+1/8-1/10+1/9-1/11)
=1/2(1-1/3+1/2+1/8-1/10-1/11)