1/1x3+1/3x5+1/5x7+1/7x9+1/9x11=?

分类: 作业答案 • 2021-12-20 05:36:00

问题描述：

答

1/(1×3)+1/(3×5)+1/(5×7)+1/(7×9)+1/(9×11)
=(1/2)(1-1/3+1/3-1/5+1/5-1/7+1/7-1/9+1/9-1/11)
=(1/2)(1-1/11)
=(1/2)(10/11)
=5/11

答

=1/2×（1-1/3+1/3-1/5+1/5-1/7+17-1/9+1/9-1/11）
=1/2×（1-1/11）
=1/2×10/11
=5/11