Question

1+1/2+1/6+1/12+1/20+1/30 等于多少 还要告诉我道理是什么

Answer 1

1/2=1-1/2

1/6=1/2-1/3

1/12=1/3-1/4

……

1+1/2+1/6+1/12+1/20+1/30

=1+1-1/2+1/2-1/3+1/3-1/4+1/4-1/5+1/5-1/6

=2-1/6

=11/6